Objective type questions on Electric Current, Ohm’s Law, Resistance, Kirchhoff’s Law, Measuring Instruments and current electricity with answers.

### Electric Current Physics Quiz:

**Ques.** What constitutes current in a metal wire?

(a) Electrons

(b) Protons

(c) Neutrons

(d) None of these

**Ques.** If a 0.1 % increase in length due to stretching, the percentage increase in its resistance will be

(a) 0.2 %

(b) 2 %

(c) 1 %

(d) 0.1 %

**Ques.** When electric current passes through a wire it behaves like a

(a) Fuse

(b) Battery

(c) Magnet

(d) Element

**Ques.** If resistance of voltmeter is 10000 ohm and resistance of ammeter is 2 ohm then find *R *when voltmeter reads 12*V* and ammeter reads 0.1 *A*

(a) 118 ohm

(b) 120 ohm

(c) 124 ohm

(d) 114 ohm

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**Ques.** A piece of wire of resistance 4 *ohm*s is bent through 180^{o} at its mid point and the two halves are twisted together, then the resistance is

(a) 8 ohms

(b) 1 ohm

(c) 2 ohms

(d) 5 ohms

**Ques.** A potentiometer consists of a wire of length 4 *m* and resistance 10 ohm. It is connected to a cell of e.m.f. 2 *V*. The potential difference per unit length of the wire will be

(a) 0.5 V/m

(b) 2 V/m

(c) 5 V/m

(d) 10 V/m

**Ques.** Resistance in the two gaps of a *meter* bridge are 10 *ohm* and 30 *ohm* respectively. If the resistances are interchanged the balance point shifts by

(a) 33.3 cm

(b) 66.67cm

(c) 25 cm

(d) 50 cm

**Ques.** It is easier to start a car engine on a hot day than on a cold day. This is because the internal resistance of the car battery

(a) Decreases with rise in temperature

(b) Increases with rise in temperature

(c) Decreases with a fall in temperature

(d) Does not change with a change in temperature

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**Ques.** The equivalent resistance of resistors connected in series is always

(a) Equal to the mean of component resistors

(b) Less than the lowest of component resistors

(c) In between the lowest and the highest of component resistors

(d) Equal to sum of component resistors

**Ques.** An ammeter whose resistance is 180 ohm gives full scale deflection when current is 2 *mA*. The shunt required to convert it into an ammeter reading 20 *mA* (in *ohm*s) is

(a) 18

(b) 20

(c) 0.1

(d) 10

**Ques.** A potentiometer having the potential gradient of 2 *mV */*cm* is used to measure the difference of potential across a resistance of 10 *ohm*. If a length of 50* cm* of the potentiometer wire is required to get the null point, the current passing through the 10 *ohm* resistor is (in *mA*)

(a) 1

(b) 2

(c) 5

(d) 10

**Ques.** The reciprocal of resistance is

(a) Conductance

(b) Resistivity

(c) Voltage

(d) None of these

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**Ques.** The internal resistance of a cell depends on

(a) The distance between the plates

(b) The area of the plates immersed

(c) The concentration of the electrolyte

(d) All the these

**Ques.** The tangent galvanometer, when connected in series with a standard resistance can be used as

(a) An ammeter

(b) A voltmeter

(c) A wattmeter

(d) Both an ammeter and a voltmeter

**Ques.** Which is a *wrong* statement?

(a) The Wheatstone bridge is most sensitive when all the four resistances are of the same order

(b) In a balanced Wheatstone bridge, interchanging the positions of galvanometer and cell affects the balance of the bridge

(c) Kirchhoff’s first law (for currents meeting at a junction in an electric circuit) expresses the conservation of charge

(d) The rheostat can be used as a potential divider

**Ques.** The resistivity of a wire depends on its

(a) Length

(b) Area of cross-section

(c) Shape

(d) Material

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**Ques.** Potential gradient is defined as

(a) Fall of potential per unit length of the wire

(b) Fall of potential per unit area of the wire

(c) Fall of potential between two ends of the wire

(d) Potential at any one end of the wire

**Ques.** The current in a simple series circuit is 5.0 *amp*. When an additional resistance of 2.0 *ohms *is inserted, the current drops to 4.0 *amp*. The original resistance of the circuit in ohms was

(a) 1.25

(b) 8

(c) 10

(d) 20

**Ques.** A galvanometer can be converted into an ammeter by connecting

(a) Low resistance in series

(b) High resistance in parallel

(c) Low resistance in parallel

(d) High resistance in series

**Ques.** A uniform wire of resistance 9 ohm is cut into 3 equal parts. They are connected in the form of equilateral triangle *ABC*. A cell of e.m.f. 2 *V* and negligible internal resistance is connected across *B* and *C*. Potential difference across *AB* is

(a) 1 V

(b) 2 V

(c) 3 V

(d) 0.5 V

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**Ques.** The material of wire of potentiometer is

(a) Copper

(b) Steel

(c) Manganin

(d) Aluminium

**Ques.** A copper wire of resistance *R* is cut into ten parts of equal length. Two pieces each are joined in series and then five such combinations are joined in parallel. The new combination will have a resistance

(a) R

(b) R/4

(c) R/5

(d) R/25

**Ques.** An energy source will supply a constant current into the load if its internal resistance is

(a) Zero

(b) Non-zero but less than the resistance of the load

(c) Equal to the resistance of the load

(d) Very large as compared to the load resistance

**Ques.** A wire of resistance R is divided in 10 equal parts. These parts are connected in parallel, the equivalent resistance of such connection will be

(a) 0.01 R

(b) 0.1 R

(c) 10 R

(d) 100 R

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**Ques.** Current provided by a battery is maximum when

(a) Internal resistance equal to external resistance

(b) Internal resistance is greater than external resistance

(c) Internal resistance is less than external resistance

(d) None of these

**Ques.** The length of the wire is doubled. Its conductance will be

(a) Unchanged

(b) Halved

(c) Quadrupled

(d) 1/4 of the original value

**Ques.** For driving a current of 2 *A* for 6 *minutes* in a circuit, 1000 *J* of work is to be done. The e.m.f. of the source in the circuit is

(a) 1.38 V

(b) 1.68 V

(c) 2.04 V

(d) 3.10 V

**Ques.** By increasing the temperature, the specific resistance of a conductor and a semiconductor

(a) Increases for both

(b) Decreases for both

(c) Increases, decreases

(d) Decreases, increases

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**Ques.** A torch battery consisting of two cells of 1.45 *volts *and an internal resistance 0.15 ohm, each cell sending currents through the filament of the lamps having resistance 1.5*ohm*s. The value of current will be

(a) 16.11 amp

(b) 1.611 amp

(c) 0.1611 amp

(d) 2.6 amp

**Ques.** The resistance of a conductor is 5 *ohm* at 50^{o}*C* and 6 *ohm* at 100^{o}*C*. Its resistance at 0^{o}*C* is

(a) 1 ohm

(b) 2 ohm

(c) 3 ohm

(d) 4 ohm

**Ques.** By a cell a current of 0.9 A flows through 2 *ohm* resistor and 0.3 A through 7 *ohm* resistor. The internal resistance of the cell is

(a) 0.5 ohm

(b) 1.0 ohm

(c) 1.2 ohm

(d) 2.0 ohm