Forms Of Energy Worksheet (Page 4 of 4) in pdf

2.5 What Is the Efficiency of a Series of Energy Conversions?

Connect a small light bulb to a solar cell. Shine the large flood light onto the solar

cell so that the small bulb lights.

(Next, you will try to light the small bulb by shining another small bulb onto the solar

cell. Before you try this activity, predict what you think will happen when the small

bulb shines on the solar cell.

Making predictions can help you learn physics by

identifying your ideas about how the world works, as well as make the course more

interesting. An incorrect prediction does not hurt your grade.)

Predict whether the small light bulb will light when another small bulb shines on the

solar cell. Then try the activity and write the outcome in the answer blank.

Prediction: _____________

Answer:____________

Will the small bulb light?

1) Explain why the small bulb did or did not light when a small bulb shines on the

solar cell.

2) What form of energy goes into the solar cell? ______________________

3) What form of energy lights the bulb? _________________________

4) What form of energy is wasted when the bulb lights? ___________

Find the efficiency of the conversion process that turns radiant energy shining on the

solar cell into visible light from the small bulb.

1) If the solar cell requires 100 joules of radiant energy to produce 25 joules of

electrical energy, find the efficiency of this step of the conversion process.

_____________

2) If 25 joules of electrical energy are converted into 5 joules of visible light in the

small bulb, find the efficiency of this step of the process.

_____________

3) Use the answers to parts 1) and 2) to find the overall efficiency when this solar

cell is used to light the small bulb.

______________

Group Discussion Question: When the solar cell lights the small bulb, the majority of

the radiant energy shining on the solar cell is wasted. List the places where energy is

wasted. Which forms of energy are wasted?

Forms Of Energy Worksheet Page 4