Power Dissipated

Which one of the following quantities is equivalent to 1 W?

• 1 V/A

• 1 Ω • m

• 1 V • A

• 1 V/Ω

A kilowatt-hour is equivalent to

• 1000 W.

• 3600 J.

• 3,600,000 J/s.

• 3,600,000 J.

If the resistance in a constant voltage circuit is doubled, the power dissipated by that circuit will

• increase by a factor of two.

• increase by a factor of four.

• decrease to one-half its original value.

• decrease to one-fourth its original value.

If the voltage across a circuit of constant resistance is doubled, the power dissipated by that circuit will

• be four times as large.

• be two times as large.

• decrease to one-half the original power.

• decrease to one-fourth the original power.

What potential difference is required across an 8.0-Ω resistor to cause 2.0 A to flow through it?

• 4.0 V

• 16 V

• 8.0 V

• 32 V

A 4000-Ω resistor is connected across a 220-V power source. What current will flow through the resistor?

• 0.055 A

• 1.8 A

• 5.5 A

• 18 A

Tags

NGSS.HS-PS2-5

A resistor operated at 140 V dc is rated at 1.40 kW.

(a) What is the normal operating current through the resistor?

(b) What is the resistance of the resistor?

• (a) 10 A . (b) 14 Ω

• (a) 14 A . (b) 14 Ω

• (a) 10 A . (b) 10 Ω

• (a) 0.010 A . (b) 14000 Ω

An instrument is rated at 240 W if it is connected across a 120-V dc power supply.

(a) What current does it draw under normal operation?

(b) What is its resistance?

• (a) 0.20 A (b) 360 Ω

• (a) 60 A (b) 2.0 Ω

• (a) 2.0 A (b) 60 Ω

• (a) 0.2 A (b) 60 Ω

Tags

NGSS.HS-PS2-4

A 200-W light bulb is connected across a 100-V dc power supply. What current will flow through this bulb?

• 0.90 A

• 0.36 A

• 0.60 A

• 2.0 A

A 100-W light bulb is operated by a 110-V dc source. What is the resistance of this bulb?

• 100 Ω

• 8.0 × 10^-3 Ω

• 120 Ω

• 240 Ω