### CHAPTER # 13 CURRENT ELECTRICITY

If the length and diameter of conductor is double, the
resistance is

a) Remain same                  b) Double
c) Half                                d) Four time

The reciprocal of resistivity is called

a)     Resistance
b)    Conduction
c)     Conductivity
d)    None

One coulomb per second is equal to

a)     Joule
b)    Volt
c)     Ampere
d)    Walt

In the metallic conductor the current is due to flow of charge

a)     Positive
b)    Negative
c)     Proton
d)    None

Conventional current flow from

a)     Positive to negative
b)    Negative to positive
c)     Negative to negative
d)    None

The main source for the current are

a)     Two
b)    Three
c)     Four
d)    Five
The drift velocity of electron at 0oC is

a)     zero
b)    Maximum
c)     1 cm/sec
d)    10 cm/sec

In the thermocouple the heat energy is converted
into

a)     Mechanical energy
b)    Electric energy
c)     Magnetic energy
d)    None

An electric heater 220V, 440W has a resistance

a)     2 Ω
b)    110 Ω
c)     0.5 Ω
d)    20 Ω

The heating effect of current utilized in

a)     Iron
b)    Tube light
c)     Fan
d)    Motor

Mathematical form of ohm’s law is

a)     I = VR
b)    I = V/R
c)     I = R/V
d)    R = IV

Ohm’s law is valid for only current flowing in

a)     Conductors
b)    Transistors
c)     Diodes
d)    Electric Areas

Through an electrolyte electric current is passed due to drift of

a.     Free electrons
b.    Positive and negative ions
c.     Free electrons and holes
d.    Protons

The e.m.f. of two cells can be compared by

a.     AVO meter
b.    Voltmeter
c.     Potentiometer
d.    Galvanometer

The post office box is based on the principle of

a.     Galvanometer
b.    Wheat-stone bridge
c.     Voltmeter
d.    None

At null point the current through the galvanometer
is

a)     Zero
b)    Maximum
c)     Minimum
d)    None

A current of 10A flows in a conductors of 10 Ω
resistance for 1 mint the heat produce will be

a)     102 J
b)    6 x 102 J
c)     6 x 103 J
d)    6 x 104 J

The unit of conductivity is

a.     Ω. M
b.    (η.m)-1
c.     Ω.m-1
d.    None

When the bulb is turned on, ohm’s law is
applicable

a)     Yes
b)    No
c)     May or may not
d)    None

In series circuit the net resistance is

a.     Increase
b.    Decrease
c.     Remain constant
d.    None

Joule law can be expressed as

a)     I2 Rt
b)    IR2t
c)     IRt2
d)    V2/R

The graph b/w V and I in case of ohm law is

a)     Parabolic
b)    Curve
c)     Slope
d)    Straight line

Resistance of supper conductor is

a)     Finite
b)    Infinite
c)     Zero
d)    Changes with material

The e.m.f. of a cell or battery is the voltage b/w its
terminals, when

a.     It is closed circuit
b.    It is open circuit
c.     Its internal resistance is zero
d.    None

The S.I unit of e.m.f. is same as

a.     Work
b.    Energy
c.     Power
d.    Voltage

The main type of resistors are

a.     Two
b.    Three
c.     Four
d.    Five

In the carbon resistor their value can be find by
their

a.     Wires
b.    Terminals
c.     Color
d.    Spots

The third band is written in the form of power of

a.     2
b.    6
c.     8
d.    10

Tolerance color means

a.     Greater
b.    Less
c.     Greater-less
d.    None

If the first color red and 2nd band is green and
third band is orange, then value of resistance is

a.     20000
b.    24000
c.     25000
d.    None

If the tolerance color is gold then it value is

a.     ± 2%
b.    ± 4%
c.     ± 5%
d.    ± 6%

A variable resistors is called

a.     Resistance
b.    Rheostat
c.     Amplifier
d.    None

A heat sensitive resistor is called

a.     Amplifier
b.    Diode
c.     Thermistor
d.    Conductor

The temperature co-efficient of thermistor is

a.     Positive
b.    Negative
c.     Zero
d.    None

Thermistor can be used for the accurate
measurement of

a.     Voltage
b.    Resistance
c.     Temperature
d.    Heat

A circuit which has only one voltage source is
called

a.     Network
b.    Simple circuit
c.     Complex circuit
d.    None

The circuit who has more than one voltage source
is called

a.     Network
b.    Simple circuit
c.     Complex circuit
d.    None

The algebraic sum of all the current at junction is
zero, is Kirchoff’s

a.     1st law
b.    2nd law
c.     3rd law
d.    4th law

The algebraic sum of voltages changes around a
closed circuit or loop is zero, is Kirchoff’s

a.     1st law
b.    2nd law
c.     3rd law
d.    4th law

If the resistance of a certain length wire, diameter
5mm is 10Ω if the diameter is charge to 10mm,
then new resistance is

a.     40
b.    5
c.     20
d.    2.5

The unit for the consumption of electrical energy
commonly used is

a.     Joule
b.    Watt sec
c.     K. watt. hr
d.    Watt. hr

Heat generated by 40 watt bulb is one hour is

a.     24000 J
b.    48000 J
c.     144000 J
d.    14400 J

The principle of potentiometer

a.     P.d  length
b.    P.d  resistance
c.     P.d.  area
d.    None

A fuse is placed in series with circuit to protect
against

a.     High power
b.    High voltage
c.     High current
d.    Over heating

If the resistor is traversed apposite to the direction
of current, then potential is

a.     Positive
b.    Negative
c.     Zero
d.    None

When electricity passes through the liquid then
process is called

a.     Electro late
b.    Electrolysis
c.     Electro-conductor
d.    None

Which one gives pure nature of the material

a.     Resistively
b.    Conductivity
c.     Temperature co-efficient
d.    None

Kirchoff’s 1st law is also called law of conservation of

a.     Charge
b.    Mass
c.     Energy
d.    None

The resistivity of a material is . If the area of cross-section of material is doubled and length is halved then the resistivity of material is:

a)                                   b) 4
c) 2                                  d)  / 4

Four bulbs of 10W, 20W, 30W and 40W are connected in parallel, the bulb that will shine more is

a) 10W                                b) 20W
c) 30W                                d) 40W

A source of 200V provides a current of 10.0 Amperes to a house. The power delivered by the source is

a) 20 watt                b) 40 watt
c) 2000 watt                        d) 200 watt

When the battery is connected at its ends, an electric field is set up at

a) Its ends               b) Every point
c) Middle                d) All of them

The value of resistance depends upon

a) Nature                 b) Dimension
c) Physical state      d) All of them

Conductance is a quantity used to describe the

a) Physical state of the conductor
b) Electrical properties of material
c) Dimension of the conductor
d) All of them

The resistivity  of  Aluminium in Ωm is

a) 2.59 × 10-8                       b) 2.60 × 10-8
c) 2.63 × 10-8                       d) None of these

The resistivity of Germanium in Ωm is

a) 0.7 × 10-8             b) 0.5 × 10-8
c) 0.59 × 10-8                       d) None of these

The colour code for the colour Grey is

a) 7                         b) 8
c) 9                         d) 5

A zero ohm resistor is indicated by

a) A single silver colour band
b) A single black band
c) A silver black band
d) None of these

Thermo couples convert heat energy into

a) Mechanical energy           b) Chemical energy
c) Electrical energy d) None of these

An accurate measurement of emf of a cell is made by

a) A voltmeter                     b) An ammeter
c) A potentiometer   d) All of them

Do bends in a wire affect its electrical resistance

a) Yes                           b) No
c) Affects a little                        d) None of these

A 50 volt battery is connected across a 10 ohm resistor. The current is 4.5A. The internal resistance of the battery is:

a) 1.1 Ω                              b) 1.2 Ω
c) 1.3 Ω                              d) 1.4 Ω

A 25 watt and 40 watts bulbs were connected  an a series to a 220V line. Which electric bulb will grow more brightly?

a) 25 watts bulb                   b) Neither will give light
c) Both will have same incandescence
d) none

### COMMON COLLECTOR CONFIGURATION OF A TRANSISTOR

COMMON COLLECTOR CONNECTION

In  this  configuration  the  input  is  applied  between the  base  and  the  collector and  the  output  is  taken  from  the  collector  and  the  emitter.  Here  the  collector  is common to both the input and the output circuits as shown in Fig.

Common Collector Transistor Circuit

In  common  collector  configuration  the  input  current  is  the  base current  IB  and  the output current is the emitter current IE. The ratio of change in emitter current to the  change in the base current is called current amplification factor.

It is represented by

COMMON COLLECTOR CIRCUIT

A test  circuit  for determining the  static characteristic  of an NPN transistor is shown in Fig. In this circuit the collector is common to both the input and the output circuits.   To   measure   the   base   and   the   emitter   currents,   milli   ammeters   are connected in series with the base and the emitter circuits. Voltmeters are connected   across the input an…