Electricity

A student carries out an experiment and plots

the V-I graph of three samples of nichrome wire

with resistances R₁, R₂ and R₃ respectively . Which of the following is true?

• R₁=R₂=R₃

• R₁>R₂>R₃

• R₁<R₂<R₃

• R₂>R₃>R₁

If the current I through a resistor is increased by

50% (assume that temperature remains unchanged), the increase in power dissipated will be

• 50%

• 75%

• 125%

• 225%

The resistivity does not change if

• both material and temperature are changed

• the shape of the resistor is changed

• the material is changed

• the temperature is changed

In an electrical circuit two resistors of 4 Ω and 8 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be

• 5J

• 10J

• 20J

• 30J

An electric kettle consumes 2.5 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?

• 5A

• 10A

• 12A

• 15A

Two resistances are joined in parallel whose resultant is 16/3 Ω. One of the resistance wire is broken and the effective resistance becomes 8 Ω. Then the resistance in ohm of the wire that got broken was?

• 4Ω

• 6Ω

• 16Ω

• 24Ω

Two electrical devices with power rating 3 W and 5 W , whose series combination is connected across a voltage source with potential difference 16 V. Find the resistance of 3 W device.

• 3 Ω

• 6 Ω

• 12 Ω

• 15 Ω

A current of 0.25 A is drawn by a filament of an electric bulb for 5 minutes. Find the amount of electric charge that flows through the

circuit.

• 75 C

• 125 C

• 200 C

• 300 C

36 J of work is done in moving certain charge across two points having a potential difference 1.2 V. Find the magnitude of charge.

• 3 C

• 1/3 C

• 30 C

• 1/30 C

An electric refrigerator rated 250 W operates 10 hour/day. What is the cost of the energy to operate it for 20 days at ₹ 5.00 per kW h?

• ₹ 300

• ₹ 250

• ₹ 200

• ₹ 100