1. A 5 Ohm resistor is connected to a 9 Volt battery. How many Joules of thermal energy are produced in 7 minutes?

2. The current in a flashlight powered by 4.5 Volts is 0.5 A. What is the power delivered to the flashlight?

3. If the flashlight in the previous problem is left on for 3 minutes, how much electric energy is delivered to the bulb?

4. A 50 Ohm resistance causes a current of 5 milliamps to flow through a circuit connected to a battery. What is the power in the circuit?

5. How many Joules of electric energy are delivered to a 60 Watt lightbulb if the bulb is left on for 2.5 hours?

Question 1: 189 joules

Question 2: 2.25 watts

Question 3: 405 joules

Question 4: 0.00125 watts

Question 5: 450000 joules

Explanation:

question 1:

Volt=1.5v

Resistance = 5 ohms

Time=7 minutes

Time=7 x 60

Time=420 seconds

Current = voltage ➗ resistance

Current = 1.5 ➗ 5

Current = 0.3 amps

Energy=current x voltage x time

Energy=0.3 x 1.5 x 420

Energy = 189 joules

Question 2:

Current = 0.5 amps

Voltage = 4.5v

Power=current x voltage

Power=0.5 x 4.5

Power=2.25 watts

Question 3:

Current=0.5 amps

Voltage=4.5v

Time = 3 minutes

Time = 3x60

Time = 180 seconds

Energy=current x voltage x time

Energy=0.5 x 4.5 x 180

Energy = 405 joules

Question 4:

Resistance=50 ohms

Current = 5 milliamps

Current = 5/1000

Current = 0.005 amps

Power = current x current x resistance

Power=0.005 x 0.005 x 50

Power=0.00125 watts

Question 5:

Power = 50 watts

Time=2.5 hour

Time=2.5 x 60 x 60

Time = 9000 seconds

Energy=power x time

Energy=50x9000

Energy=450000 joules