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CBSE

NEET Physics : Current Electricity

Multiple Choice Questions

71.

The ammeter shown in figure consists of a 480 Ω coil connected in parallel to a 20 Ω shunt. The reading of ammeter is

0.125 A
1.67 A
0.13 A
0.67 A

72.

Find equivalent resistance between X and Y

73.

A copper rod of length 20 cm and cross-sectional area 2 mm is joined with a similar aluminium rod as shown below

The resistance of pair of rods is (ρ_Al =2.6 x 10^-8 Ω-m and ρ_Cu =1.7 x 10^-8 Ω-m)

1.0 mΩ
2.0 mΩ
3.0 mΩ
None of these

74.

In the given figure, potential difference between A and B is

0 V
5 V
10 V
15 V

75.

The electron of H - atom is revolving around the nucleus in circular orbit having radius $\frac{h^{2}}{4 π {me}^{2}}$ with $(\frac{2 π e^{2}}{h})$ . The current produced due to the motion of electron is

$\frac{2 π m^{2} e^{2}}{3 h^{2}}$
zero
$\frac{2 π^{2} me}{h^{2}}$
$\frac{4 π^{2} {me}^{5}}{h^{3}}$

76.

A engine pumps up 100 kg of water through a height of 10 m in 5s. Given that, the efficiency of engine is 60%. If g = 10 ms^-2, the power of this engine is

3.3 kW
0.33 kW
0.033 kW
33 kW

77.

When plate voltage in diode valve is increased from 100V to 150V. Then, plate increases from 7.5 mA to 12 mA, then dynamic plate resistance will be

10 kΩ
11 kΩ
15 kΩ
11.1 kΩ

78.

The galvanometer resistance is 30 Ω and it is connected to 2 V battery along with a resistance 2000 Ω in series. A full scale deflection of 25 divisions is obtained. In order to reduce this deflection to 20 divisions, the resistance in series should be