Q.1: (a) The normal body temperature is 98.4o F. What is this temperature on Celsius scale? (b) At what
temperature do the Fahrenheit and Celsius
scales coincide?
Q.2: A steel rod has a length of exactly 0.2 cm at 30o C. What will be its length at 60o C?
Q.3: Find the change in volume of an aluminium sphere of 0.4 m radius when it is heated from 0 to 100o C.
Q.4: Calculate the root mean square speed of hydrogen molecule at 800K.
Q.5: (a) Determine the average value of the kinetic energy of the particles of an ideal gas at 0o C and at 50o
C. (b) What is the kinetic energy per mole of
an ideal gas at these temperatures?
Q.6: A 2 kg iron block is taken from a furnace where its temperature was 650o C and placed on a large block
of ice at 0o C. Assuming that all
the heat given up by the iron is used to melt the ice, how much ice is melted.
Q.7: In a certain process 400 J of heat are supplied to a system and at the same time 150 J of work are done by the system. What is the increase in the internal energy of the system?
Q.8: There is an increase of internal energy by 400 joules when 800 joules of work is done by a system.What is the amount of heat supplied during this process?
Q.9: A heat engine performs 200 J of work in each cycle and has efficiency of 20 percent. For each cycle of operation (a) How much heat is absorbed and (b) How much heat is expelled?
Q.10: A heat engine operates between two reservoirs at temperature of 25o C and 300o C. What is the maximum efficiency for this engine?
Q.11: The low temperature reservoir of a Carnot engine is at 7o C and has efficiency 40%. It is desired to increase the efficiency to 50%. By how much degree the temperature of hot reservoir is increased.
Ch # 12 | Electrostatics
Q.1: Two unequal point charges repel each other with a force of 0.2 newtons when they are 10 cm apart. Find the force which each exerts on the other when they are: (i) 1 cm apart (ii) 5 cm apart
Q.2: Two point charges of +1x10-4 and –1x10-4 coul are placed at a distance of 40 cm from each other. A Charge +6x10-5 coul is placed midway between them. What is the magnitude and direction of force on it.
Q.3: Three point charges each of 4μ.C. are placed at the three corners of a square of side 20 cm. Find the magnitude of the force on each.
Q.4: Three charges Q1 = +7x10-6 C, Q2 = -4x10-6 C, Q3 = -5x10-6 C, are placed at the vertices of a measure 3, 4 and 5 cm. Determined the magnitude and direction of the force on the charge Q1 .
Q.5: Two small spheres, each having a mass 0.1 gm, are suspended from the same point by silk threads each cm apart. Find the change on each. 20 cm long. The spheres are given equal charges and they are found to repel each other, coming to rest 24
Q.6: Two charges of +2x10-7 C and -5x10-7 C are placed at a distance of 50 cm from each other. Find a point on the line joining the charges at which the electric field is zero.
Q.7: What are the electric field and potential at the centre of a square whose diagonals are 60 cm, each when (a) charges each of 2μc are placed at the four corners. (b) charges of +2μc on adjacent corners and -4μc on other corners.
Q.8: A particle carrying a charge of 10-5 C starts from rest in a uniform electric field of intensity 50 Vm-1. Find the force on the particle and the kinetic energy it acquires when it has moved 1 m.
Q.9: A proton of mass 1.67 x 10-27 kg and charge 1.6 x 10-19 C is to be held motionless between two horizontal parallel plates 10 cm apart. Find the Voltage required to be applied between the plates.
Q.10: A small sphere of weight 5 x 10-3 N is suspended by a silk thread 50 mm long which is attached a point on a large charged insulating plane. When a charge of 6 x 10-8 C is placed on the ball the thread makes an angle of 30o with the vertical. What is the charge density on the plane.
Q.11: How many electrons should be removed from each of the two similar spheres each of 10 g so that electrostatic repulsion be balanced by gravitational force.
Q.12: There is a potential difference of 150 volts between two conductors of a power line. A charge of 600 C is carried from one conductor to the other. What work is required? If the time necessary to transport the charge is 1.25 s how much power is used?
Q.13: A metal sphere of 100 mm radius has a charge of 4.25x10-9 coul. What is the potential? (a) at its surface (b) at its centre. What is the energy of a charge of 2.5x10-6 C at a point 150 mm from the centre of sphere?
Q.14: An electron having an initial of 10+3 ms-1 is directed from a distance of 1 mm at another electron whose position is fixed. How close to the stationary electron will the other approach.
Q.15: Find the equivalent capacitance and charge on each of the capacitor shown in the diagram.
Q.16: Two capacitors of 2μf and 8μf are joined in series and a potential difference of 300 volts is applied. Find the charge and potential difference for each capacitor.
Q.17: A capacitor of 100 pF is charged to a potential difference of 50 volts. Its plates are then connected in parallels to another capacitor and it is found that the potential difference between its plates falls to 35 volts. What is the capacitance of the second capacitor?
Q.18: Find the equivalent capacitance of the shown in the diagram.
Q.20: Three 1.0 pF capacitors are charged separately to the potential difference of 100, 200 and 300 volts. The capacitors are then joined in parallels. What is the resultant potential difference?
Q.21: Compare the capacitances of two identical capacitors with dielectrics inserted as shown in the diagram. The dielectric constants are K1 and K2.
Q.22: A capacitor of 10 μf and one 20 μf are connected across batteries of 600 volts and 1000 volts respectively and then disconnected. They are then joined in series. What is the charge on each capacitor?
Q.23: Attempt the problem 22 with the difference that the capacitors are joined in series after being charged, as before.
Ch # 13 | Current Electricity
1. Electric Current &
Resistivity
Q.1A certain battery is rated at 80 ampere hour. How many coulomb of charge can this battery supply?
Q.2: A silver wire 2 m long is to have a resistance of is to have a resistance of 0.5 ohm.What sould its diameter be?
Q.5: A wire carries a current of 1 A. How many electrons pass a point in the wire an each second?
Q.12: A 40Ω resistor is to be wound from platinum wire 0.1mm in diameter. How much wire is needed? (= 11 x 10-8 Ω.m)
Q.3: A current of 6 A is drawn from a 120 V line. What power is being developed? How much energy in joule and in Kwh is expended if the current is drawn steadily for one week.
Q.4: Currents of 3 A and 1.5 A flow through two wires, one that has a potential difference of 60 V across its ends and another that has a potential difference of 120 V across its ends. Compare the rate at which energy pass through each wire.
Q.6: An electric drill rated at 400 W is connected to a 240 V power line. How much current does it draw?
Q.13: The battery of a pocket calculator supplies 0.35 A at a p.d. of 6 V. What is the power rating of the calculator?
Q.14: A current of 5 A through a battery is battery is maintained for 30 s and in this time 600 J of chemical energy is transformed into electric energy (a) What is the e.m.f of the battery? (b) How much electric power is available for heating and other uses?
Q.19: A water heater that will deliver 1kg of water per minute is required. The water is supplied at 20o C and an output temperature of 80o C is desired. What should be the resistance of the heating element in the water if the line voltage is 220V? (Given sp. Heat capacity of water = 4200 J kg-1 K-1)
Q.20: Prove that the rate of heat production in each of the two resistors connected in parallel are inversely proportional to the resistance.
Q.21: A 240-V cloth dryer draws a current of 15A. How much energy in kWh and joules does it use in 45 minutes operation and how much will be the cost at the rate of Rs. 1.45 per unit of electric energy?
4. Combination of Resistances (Part
1)
Q.7: Resistors of 20 Ω, 40 Ω, 50 Ω are connected in parallel across a 50 V power source. Find the equivalent resistance of the set and the current in each resistor?
Q.8: (a) Find the equivalent resistance of the network shown in figure. (b) What is the current in 8-Ω resistor if the p.d. of 12V is applied to the network?
5. Combination of Resistances
(Part 2)
Q.9: A 60-V potential difference is applied to the circuit shown below. Find the current in the 10-Ω resistor.[Hint Reduce the circuit bring out the series and parallel combination of the resistors more clearly].
Q.15: A 12 Ω resistor is connected in series with a parallel combination of 10 resistors, each of 200Ω. What is the net resistance of the circuit?
Q.16: Three equal resistors each of 12 Ω can be connected in four different ways. What is equivalent resistance of each combination?
6. Internal Resistance and EMF
Q.10: A source of what potential difference is
needed to charge a battery of 20 V e.m.f and internal resistance of 0.1 Ω at a
rate of 70 A.
Q.11: A battery of 24V is connected to a 10Ω load and a current of 2.2 amp is drawn; find the internal resistance of the battery and its terminal voltage.
7. Temperature Co efficient of
Resistance
Q.17: Find the resistance at 50o C
of a copper wire 2 mm in diameter and 3 m long.
Q.18: The resistance of a tungsten wire used in the filament of a 60 W bulb is 240Ω when the bulb is hot at a temperature of 2020o C. What would you estimate its resistance at 20o C? (Given α = 0.0046oC-1)
Q.22: A resistor is made by winding on a spool a 40m length of constantan wire of diameter 0.8 mm. Calculate the resistance of the wire at (a) 0o C (b) 50o C. [Assume ρo at 0o C = 49 x 10-8 Ω. m. and α = 1 x 10- 5 C-1].
Ch # 14 | Magnetism and Electromagnetism
Q.1: A horizontal straight wire 5 cm long weighing 1.2 gm-1 is placed perpendicular to a uniform horizontal field of 0.6 webers-m-2. If the resistance of the wire is 3.8 Ω m-1. Calculate the potential difference to be applied between the ends of the wire to make it just self supporting.
Q.2: A cathode ray tube is set up horizontally with its axis N-s and surrounded by a magnetic shield. If the voltage across the tube is 900 volts, the distance from electron gun to the screen is 10 cm and vertical component of earth’s field is 0.45x10-4 webers/m2 . Calculate by how much the spot is moved. Given that e/m = 1.8x1011 Ckg-1
Q.3: What is the flux density at a distance of 0.1 m in air from a long straight conductor carrying a current of 6.5 amperes? Hence calculate the force per meter on a similar parallel conductor at a distance of 0.1 m from the first and carrying a current of 3 amperes. Will the wires attract or repel, if the directions of currents in the two wires are opposite to each other? Explain how the expression of force between two such conductors is used to define ampere.
Q.4: A straight metal rod 50 cm long can slide with negligible friction on parallel conducting rails. It moves at right angles to a magnetic field 0.72 webers-m2 . The rails are joined to a batter of emf 3 volts and a fixed series resistance of 1.6 Ω. Find the force required to hold the rod at rest.
Q.5: It is required to produce inside a toroid a field of 2x10-3 webers-m3 . The toroid has a radius of 15 cm and 300 turns. Find the current required for this purpose. If toroid is wound on an iron core of permeability 300 times the permeability of free space what increase in B will occur for the same current.
Q.6: A proton is accelerated by a potential difference of 6x105 volts. It then enters a uniform field B = 0.3 webers-m 2 in a direction making an angle of 45o with the magnetic field, what will be the radius of the circular path?
Q.7: Two parallel metal plates separated by 5 cm of air have a potential difference of 220 volts. A magnetic field B = 5x10-3 webers-m2 is also produced perpendicular to electric field. A beam of electrons travel undeflected through these crossed electric and magnetic fields. Find the speed of electrons.
Q.8: A coil of 50 turns wound on a rectangular ivory frame 2 cm x 4 cm is pivoted to rotate in a magnetic field of 0.2 webers m-2. The face of the coil is parallel to the field. How much torque acts over the coil when a current of 0.5 amp passes through it? What will be the torque when the coil is rotated by 60o from its initial position?
Q.9: A cube 100 cm on a side is placed in a uniform magnetic field of flux density 0.2 webers-m-2, as shown in the diagram. Wires A, C and D move in the directions indicated, each at a rate of 50 cm.s-1, determine the induced emf in each wire.
Q.10: What is the mutual Inductance of a pair
of coils if a current change of 6 amps in one coil causes the flux in the
second coil of 2000 turns to change by 12x10-4 webers-m-2.
Q.11: An emf of 45 m.volt is induced in a coil
of 500 turns, when the current in a neighbouring coil changes from 10 amps to 4
amps in 0.2 seconds. (a) What is the mutual Inductance of the coils? (b) What
is the rate of change of flux in the second coil?
Q.12: An iron core solenoid with 400 turns has
a cross section area of 4.0 cm2 . A current of 2 amp passing through
it produces B = 0.5 webers-m-2. How large an emf is induced in it,
If the current is turned off in 0.1 seconds .What is the self Inductance of the
solenoid?
Q.13:
The current in a coil of 325 turns is changed from zero to 6.32 amps, there by
producing a flux of 8.46x10-4 webers. What is the self Inductance of
the coil?
Q.14: A 100 turns coil in a generator has an
area of 500 cm2 rotates in a field with B = 0.06 webers-m-2.
How fast must the coil rotated in order to generate a maximum voltage of 150
volts?
Q.15: A step down transformer at the end of a
transmission line reduces the voltage from 2400 volts to 1200 volts. The power
output is 9.0 K.W and over all efficiency of the transformer is 95%. The
primary winding has 400 turns. How many turns has the secondary coil? What is
the power input, what is the current in each of the coils?
Q.16: The overall efficiency of a transformer
is 90%. The transformer is rated for an output of 12.5 KW. The primary voltage
is 1100 volts and the ratio of primary to secondary turns is 5:1. The iron
losses at full load are 700 watts. The primary coil has a resistance of 1.82
ohms. (a) How much power is lost because of the resistance of the primary
coils? (b) What is the resistance of the secondary coils?
Ch # 15 | Electrical Measuring Instruments
Q.1: A galvanometer has a resistance of 50 Ohms
and it deflects full scale when a current of 10 milliamperes flows in it. How
can it be converted into an ammeter of range 10 amperes?
Q.2: A galvanometer whose resistance is 40 Ohms
deflects full-scale for a potential difference of 100 millivolts across its
terminals. How can it be converted into an ammeter of 5 ampere range?
Q.3: The coil of a galvanometer which has a
resistance of 50 ohms and a current of 500 micro amperes produces full-scale
deflection in it. Show by a diagram how it can be converted to (a) an ammeter
of 5 ampere range and compute the shunt resistance. (b) a volt meter of 300
volt range and compute the series resistance.
Q.4: A galvanometer of resistance 2.5 ohms
deflects full-scale for a current of 0.05 amperes. It is desired to convert
this galvanometer into an ammeter reading 25 amperes full-scale. The only shunt
available is of 0.03 ohm. What resistance R must be included in series with the
galvanometer coil as shown in figure for using this shunt
Q.5: An
ammeter deflects full-scale with a current of 5 amperes and has a total
resistance of 0.5 ohms.What shunt resistance must be connected to it to measure
25 amperes full-scale?
Q.6: A
moving coil galvanometer G has a resistance of 50 ohms and deflects full-scale
with a current of 0.005 ampere. What resistance R1, R2
and R3 must be connected to it as shown in figure to convert into a
multi-range ammeter having ranges of 1A, 5A and 10A.
Q.7: A 300-volt voltmeter has a total resistance of 20,000 ohms. What additional series resistance must be connected to it to increase its range to 500 volt?
Q.8: The resistance of a moving-coil galvanometer is 25 ohms and current of 1 milliampere causes full-scale deflection in it. If is to be converted into a multi-range voltmeter. Find the series resistance R1, R2 and R3 to give the range of 5 volts, 50 volts and 500 volts at the range terminals as shown in figure.
Q.9: The galvanometer of the Ohmmeter in figure has a resistance of 25 ohms and deflects full scale with a current of 2 milliamperes in it. The e.m.f. E of its cells is 1.5 volts. (a) What is the value of the series resistance R? (b) To what values of x connected to its terminals do the deflection of 1/5, 1/2 and 4/5 full- scale correspond? (c) Is the scale of the Ohmmeter linear?
Q.10: A constant potential difference of 25 volts is applied across a uniform resistance wire AB, 100 cm long. Terminals are soldered to three points C,D,F on the wire respectively 16, 32 and 64 cm from A, figure. Find the potential differences (between each pair of points given in the subscripts) VAD (iii) VAF (iv) VCD (v) VCF (vi) VDF (vii) VCB (viii) VDB (ix) VFB.
Q.11: A potentiometer is set up to measure the emf, Ex of cell (figure). The potentiometer wire is 120 cm long. Es is the emf of a standard cadmium cell equal to 1.018 volts. When the key 1 only is closed to include the emf Ex in the galvanometer circuit, the galvanometer gives no deflection with the sliding contact at C,56.4 cm from A. When the key 2 only is closed to include the emf Es in the galvanometer circuit the balance is obtained at C΄,43.2 cm from A. (a) What is the emf of the cell ?(b) What is the p.d across the entire length of the wire AB?
Ch # 16 | Electromagnetic Waves and Electronics
Q.1: Light is said to be a transverse wave
phenomenon. What is that varies at right angles to the direction in which a
light wave travel.
Q.2: A radar sends out 0.05 μs pulses of
microwaves whose wave length is 2.5 cm. What is the frequency of these
microwaves? How many waves does each pulse contain?
Q.3: A nanosecond is 10-9s (a) What
is the frequency of electromagnetic wave whose period is 1ns? (b) What is it’s
wave length? (c) To what class of electromagnetic waves does it belong?
Ch # 17 | Advent of Modern Physics
Q.1: In the inertial frame of a pendulum the
time period is measured to be 3 s. What will be the period of the pendulum for
an observer moving at a speed of 0.95 C with respect to the pendulum?
Q.2: What will be the length of a bar in the
stationary frame if its length along the x΄-direction is 1 m and the motion is
with a velocity 0.75 C with respect to the observer at rest.
Q.3:
Given moc2 = 0.511 MeV. Find the total energy E and the
kinetic energy K of an electron moving with a speed v = 0.85 c.
Q.4: The total energy of a proton of mass 1.67x10-27 kg is three times its rest energy. Find (a) Protons rest energy. (b) Speed of the proton. (c) Kinetic energy k of proton in eV.
Q.5: A particle of rest mass mo has a speed υ =
0.8c, Find its relativistic momentum, its kinetic energy and total energy?
Q.6: What will be the velocity and momentum of a particle whose rest mass is mo and whose kinetic energy is equal to its rest mass energy?
Q.7: The
sun radiates energy at a rate 3.8x1026 w. At what rate the mass of
sun diminishes?
Q.8: What will be the work function of a
substance for a threshold frequency of 43.9x1013 Hz?
Q.9: What will be the value of λmin
= hc / eVo, if h = 6.63x10-34 J.S, c = 3x108
ms-1. e = 1.6x10-19 C and Vo = 104
V.
Q.10: In a Compton scattering process, the
fractional change in work length of x-ray photons is 1% at an angle θ = 120o
, find the wavelength of x-ray used in the experiment.
Q.11: Find the wave length of a 2.0 g light ball moving with a velocity: (a) 1.0 mm per century (b) 1.0 m/s
Q.12: An electron exist with in a region of 10-10
m. Find its momentum, uncertainty and the approximate kinetic energy. Given: h
= 1.05x10-34 J.S and m = 9.1x10-31 kg
Q.13: Sodium surface is shined with light of
wave length 3x10-7 m. If the work function of Na 
= 2.46 eV, find the K.E of
the photoelectrons and also the cut off wave wave length λc = hc/Ø. Given: (1eV
= 1.6x10-19J)
Q.14: X-rays of wave length λo are scattered
from a carbon block at an angle of 45o with respect to theincident
beam. Find the shift in wave length. Given: h = 6.63x10-34 J.S, m =
9.11x10-31 kg and c = 3x108 m/s).
Q.15: If the electron beam in a T.V picture tube is accelerated by 10,000 V what will be the deBrogle’s wave length?
Q.16: What minimum energy photon can be used to observe an object of size 2.5x10-10 m.
Q.17: What will be the deBroglie’s wave length
associated with a mass of 0.01 kg moving with a velocity 10 m/s?
Q.18: Certain excited state of hydrogen atom
have a life time 2.5x10-19s. What will be the minimum uncertainty in
energy?
Q.19: X-rays are scattered from a target
material. The scattered radiation is viewed at an angle of 90o with
respect to the incident beam. Find the Compton shift in wave length.
Q.20: Find the frequency of a photon when an
electron of 20 KeV is brought to rest in a collision with a heavy nucleus.
Ch # 18 | Atomic Spectra
Q.1: Calculate the following (a) the orbit radius (b) the angular momentum (c) the linear momentum (d) the kinetic energy (e) the potential energy (f) the total energy for the Bohrs hydrogen atom in ground state.
Q.2: What is the wavelength of the radiation
that is emitted when a hydrogen atom undergoes a transition from the state n =
3 to n = 1.
Q.3: Light of wavelength 486.3 nm is emitted by
a hydrogen atom in Balmer series, what transitions of the hydrogen atom is
responsible for this radiation.
Q.4: In the hydrogen atoms an electron
experiences a transition from a state whose binding energy is 0.54 eV to
another state whose excitation energy is 10.2 eV (a) What are the quantum
numbers for these states? (b) Compute the wavelength of the emitted photon. (c)
To what series does this line belong?
Q.5: Photon of 12.1 eV absorbed by a hydrogen atom, originally in the ground state, raises the atom to an excited state. What is the quantum number of this state
Q.6: Find the wavelength of the first three lines of the Lyman series of hydrogen.
Q.7: In an experiment, the excitation potentials of hydrogen are found at 10.21 V and 12.10 V, three different spectral lines are emitted. Find their wavelengths.
Q.8: What minimum energy is needed in an X-ray
tube in order to produce X-rays with a wavelength of 0.1x10-10 m.
Q.9: A certain atom emits spectrum lines at 300, 400 and 1200 nm. Assuming that three energy levels are involved in the corresponding transitions; calculate the quantum of energy emitted at each wave length.
Q.10: Calculate the energy of a photon whose
frequency is (a) (i) 4x1014 Hz (ii) 20 GHz (iii) 30 MHz, Express
your answer in eV. (b) Describe the corresponding wavelengths for the photons
described in (a)
Ch # 19 | Atomic Nucleus
Q.1: When the chlorine atom of mass number 35
and charge number 17, is bombarded by proton, the resulting atom disintegrates,
emitting an α-particle. Write the equation representing the reaction.
Q.2: The half life of Radon is 3.80 days what
would be its decay constant?
.3: The atomic weight of Bromine is 79.938u and
it is composed of two isotopes of mass 78.943u and 80.942u compute the
percentage of each isotopes.
Q.4: The half life of 104Po210
is 140 days. By what percent does its activity will decrease per week?
Q.5: If a neutron would be entirely converted
into energy, how much energy would be produced? Express your answer in Joules
as well as electron volts.
Q.6: Find the binding energy of 52Te126,
Given: mp = 1.0078u, mn = 1.0086u, mTe = 125.9033u & 1 u = 931.5 MeV
Q.7: If the number of atoms per gramme of 88Ra226
is 2.66x1021 and it decays with a half life of 1622 years. Find the
decay constant and the activity of the sample.
Q.8: What will be the maximum energy of the
electron in the beta decay of 1H3 through the reaction. 1H3
--------- 2He3 + β- + γ
Q.9: Find the Q-value for the nuclear reaction.
20Ca42
(P, d) 20Ca41
Q.10: Find the energy released when two
deuterium (1H2 ) nuclei fuse together to form an alpha
particle (2He4 ).
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