Form 5 Chp 2.5 Electrical Energy and Power

A lamp changes __________ energy into light energy.

• Kinetic
• Electrical
• Sound
• Chemical

Tags

NGSS.HS-PS3-3

What is the unit of electrical power?

• watt
• volt
• ampere
• ohm

One megawatt is equivalent to:

• 10² W
• 10⁶ W
• 10²⁴ W
• 10⁸ W

A bulb of 100 W means that it will consume electrical energy at the rate of:

• 100 kJ per second.
• 100 kJ per hour.
• 100 joules per second.
• 100 joules per hour.

What will be the current drawn by an electric bulb of 1000 W when it is connected to a source of 220 V?
Remember: I = P/V

• 4.55 A
• 28800 J or 28.8 KJ
• 80 W
• 200 W

A current of 4 A flows through a 20 V car headlight bulb. Calculate the electric power.
 
Remember: I=P/V

• 80 W
• 200 W
• 2.5 A
• 4.55 A

Calculate the electric power of an electrical appliance in which 10 A of current is flowing through a resistor of 2 ohms.
 
Remember: V=IR and P=VI

• 80 W
• 200 W
• 2.5 A
• 22.5 KJ

Calculate the electric power of an electrical appliance of 20 V having a resistance of 10 ohms.
 
Remember: I=V/R and P=VI

• 200 W
• 40 W
• 2.5 A
• 79.20 KJ

Calculate the electrical energy consumed when a potential difference of 5 V is applied across a resistor of 2 ohms for 30 minutes.
 
Remember: V=IR and I=V/R

• 80 W
• 200 W
• 22500 J or 22.5 KJ
• 4500 J or 4.5 KJ

A current of 0.5 A flows through a resistance of 10 ohms for half an hour. Find the amount of electrical energy consumed by the resistance.
 
Remember:
V = IR
P = VI
E = Pt

• 22500 J or 22.5 KJ
• 4500 J or 4.5 KJ
• 79.2 W
• 2.5 A