Unit test (July)

Which charge configuration produces a uniform electric field?

• point charge

• uniformly charged infinite line

• uniformly charged infinite plane

• uniformly charged spherical shell

An electric dipole is placed at an alignment angle of 30º

with an electric field of 2 × 10⁻⁵N C⁻¹. It experiences a torque equal to 8 N m. The charge on the dipole if the dipole length is 1 cm is

• 4 mC

• 8 mC

• 5 mC

• 7 mC

The total electric flux for the following closed surface which is kept inside water

• 80q/ε₀

• q/40ε₀

• q/ 80ε₀

• q/ 160ε₀

Two identical conducting balls having

positive charges q1

and q2

are separated

by a centre to centre distance r. If they

are made to touch each other and then

separated to the same distance, the force between them will be

• less than before

• same as before

• more than before

• zero

If voltage applied on a capacitor is increased from V to 2V, choose the correct conclusion.

• Q remains the same, C is doubled

• Q is doubled, C doubled

• C remains same, Q doubled

• Both Q and C remain same

What is the value of resistance of the following resistor?

• 100 k Ω

• 10 k Ω

• 1k Ω

• 1000 k Ω

The temperature coefficient of resistance of a wire is 0.00125 per °C. At 20°C, its resistance is 1 Ω. The resistance of the wire will be 2 Ω at

• 800 °C

• 700 °C

• 850 °C

• 820 °C

The internal resistance of a 2.1 V cell

which gives a current of 0.2 A through a resistance of 10 Ω is

• 0.2 Ω

• 0.5 Ω

• 0.8 Ω

• 1.0 Ω

What is the current drawn out from the battery?

• 1A

• 2A

• 3A

• 4A

In Joule’s heating law, when R and t are constant, if the H is taken along the y axis and I² along the x axis, the graph is

• Straight line

• Parabola

• Circle

• Ellipse