﻿ The working of magnetic braking of trains is based on | Current Electricity

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Current Electricity

Multiple Choice Questions

201.

In the following network, potential at O is

• 4 V

• 3 V

• 6 V

• 4.8 V

202.

Effective resistance between A and B in the following circuit

• 10 Ω

• 20 Ω

• 5 Ω

203.

Two heating coils of resistances 10 Ω and 20 Ω are connected in parallel and connected to a battery of emf 12 V and internal resistance 1 Ω. The power consumed by them are in the ratio

• 1 : 4

• 1 : 3

• 2 : 1

• 4 : 1

204.

Of the following graphs, the one that correctly represents the I-V characteristics of a 'Ohmic device' is

205.The working of magnetic braking of trains is based oneddy current pulsating current alternating current steady current

A.

eddy current

The working of magnetic breaking of trains is based on eddy current.

206.

A cylindrical conductor of diameter 0.1 mm carries a current of 90 mA. The current density (in Am-2) is (π ≈ 3)

• 12 × 107

• 3 × 106

• 6 × 106

• 2.4 × 107

207.

A straight wire of length 50 cm carrying a current of 2.5 A is suspended in mid-air by a uniform magnetic field of 0.5 T (as shown in figure). The mass of the wire is (g = 10 ms-2)

• 250 gm

• 125 gm

• 62.5 gm

• 100 gm

208.

In meter bridge experiment, with a standard resistance in the right gap and a resistance coil dipped in water (in a beaker) in the left gap, the balancing length obtained is 'l'. If the temperature of water is increased, the new balancing

• < 1

• > 1

• = 0

• = 1

209.

The power dissipated in 3 Ω resistance in the following circuit is

• 0.25 W

• 0.75 W

• 1 W

• 0.5 W

210.

The value of I in the figure shown below is

• 21 A

• 4 A

• 8 A

• 19 A