Practice paper · Annual

An infinitely long uniformly charged wire produces an electric field of 1.8 x 10⁴ N/C at a distance of 1·0 cm. The linear charge density on the wire is:

1. A1·12 x10 -14 C/m
2. B3·08 x10 -15 C/m
3. C1·0 x 10 -9 C/m
4. D1·0 x10 -7 C/m

A wire of resistance R, connected to an ideal battery consumes a power P. If the wire is gradually stretched to double its initial length, and connected across the same battery, the power consumed will be:

1. AP/4
2. BP/2
3. CP
4. D2P

A long straight wire of radius ‘a' carries a steady current ‘I'. The current is uniformly distributed across its area of cross-section. The ratio of magnitude of magnetic field B₁ at a/2 and B₂ at distance 2a is:

1. A½
2. B1
3. C2
4. D4

Which of the following has its permeability less than that of free space?

1. ACopper
2. BAluminium
3. CCopper chloride
4. DNickel

A transformer is a device used for converting:

1. Ahigh ac voltage and large ac current to low ac voltage and small ac current
2. Bhigh ac voltage and small ac current to low ac voltage and small ac current
3. Clow ac voltage and large ac current to high ac voltage and small ac current
4. Dlow ac voltage and small ac current to high ac voltage and large ac current.

The amplitude of electric field in an electromagnetic wave in free space is 1000 V/m. The amplitude of the magnetic field in this electromagnetic wave is:

1. A3·0 × 10-3 T
2. B3·33 × 10-8 T
3. C3·0 × 1011 T
4. D3·33 × 10 -6 T

A tank is filled with liquid of (refractive index 4/3) up to a height H. A coin is placed at its bottom. The depth of the coin, when viewed along the near normal direction, will be

1. AH/4
2. B3H/4
3. CH
4. D4H/3

Two coherent sources, each of intensity I₀, produce interference pattern on a screen. The average intensity of light on the screen is:

1. Azero
2. BI₀
3. C2I₀
4. D4I₀