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CBSE

NEET Physics : Current Electricity

Multiple Choice Questions

201.

The reading of the ammeter in the following figure will be

0.8 A
0.6 A
0.4 A
0.2 A

202.

An electrical cable having a resistance of 0.2 Ω delivers 10 kW at 200 V DC to a factory. What is the efficiency of transmission ?

65 %
75 %
85 %
95 %

203.

A wire of resistance R is elongated n-fold to make a new uniform wire. The resistance of new wire

nR
n²R
2nR
2n²R

204.

Five equal resistance, each of resistance R are connected as shown in figure below. A battery of V volt is connected between A and B. The current flowing in FC will be

$\frac{3 V}{R}$
$\frac{V}{R}$
$\frac{V}{2 R}$
$\frac{2 V}{R}$

Short Answer Type

205.

Two cells each of same emf e but of internal resistances r₁ and r₂ are connected in series through an external resistance R. If the potential difference between the ends of the first cell is zero, what will be the value of R in terms of r₁ and r₂ ?

Multiple Choice Questions

206.

A wire of resistance 5 Ω is drawn out so that its new length is 3 times its original length. What is the resistance of the new wire ?

45 Ω
15 Ω
5/3 Ω
5 Ω

207.

Two identical cells each of emf E and internal resistance r are connected in parallel with an external resistance R. To get maximum power developed across R, the value of R is

$R = \frac{r}{2}$
R = r
$R = \frac{r}{3}$
R = 2r

208.

The current flowing through a wire depends on time as I = 3t² + 2t + 5. The charge flowing through the cross-section of the wire in time from t = 0 to t = 2 s is

22 C
20 C
18 C
5 C

Short Answer Type

209.

A battery of emf E and internal resistance r is connected across a pure resistive device (such as an electric heater) of resistance R. Prove that the power output of the device will be maximum if R = r.