Physics Basic Unit#7 Test

A wire of resistance 2Ω is bent in the form a circle. The resistance between the ends of any diameter is

• 1 Ω

• 0.5Ω

• 2Ω

• 8Ω

The resistance of semiconductor

• increases with increase of temperature

• does not change with change of temperature

• decreases with increase of temperature

• first decreases and then increases with increase of temperature

The temperature of a conductor is increased. The product of resistivity and conductivity

• Increases

• Decreases

• Remains constant

• May increase or decrease

The electric current in conductor is due to the flow of

• Positive charges only

• both positive and negative charges

• negative charges only

• neutral particles only

A 5 Ω constantan wire is bent to form a ring. Find the resistance across the diameter of the wire.

• 2.5 Ω

• 1.25 Ω

• 5 Ω

• 0.625 Ω

Two wires A and B are made of copper both wires are 1m long but wire A is 1mm. thick and wire B is 2mm Thick. The specific resistance

• more for A

• more for B

• same for both A and B

• cannot be compared

The drift velocity of electrons is of the order of

• 1m/s

• 10⁶m/s

• 10^-3m/s

• 3 x 10⁸ m/s

The resistance of a wire is doubled if

• its radius and length both are double

• its radius is halved and length is doubled

• its radius is doubled and length is halved

• its radius and length both are halved

The conductivity of a superconductor is

• Infinite

• very small

• very large

• zero

A 50 W, 220 V bulb and a 100 W, 220 V bulb are joined in series and connected to mains which bulb will glow brighter

• 50 W

• first 20 and then 100 w bulb

• 100 watt bulb

• neither bulb will glow