Topic 3.3: Emitting and absorbing EM radiation + Lenses

Question 1

Explain the relationship between the temperature of an object and emitted wavelength

Answer 1

• As temperature increases, the intensity of every emitted wavelength increases
• The intensity increases more rapidly for shorter wavelengths that longer wavelengths

Question 2

What happens to an object’s temperature when it emits/absorbs radiation?

Answer 2

Emits - Cools down
Absorbs - Warms Up

Question 3

How do objects heat up/cool down/stay the same temperature in terms of EM radiation?

Answer 3

Heats up - Average power that the object absorbs is more than the average power that it radiates

Cools down - Average power that the object absorbs is less than the average power that it radiates

Constant Temperature - radiates and absorbs the same average power

Question 4

What causes an increase in the Earth’s temperature?

Answer 4

• During the day, radiation is transferred to the Earth from the Sun
• Some is reflected, most is absorbed by the atmosphere, clouds and surface, causing an increase in local temperature

Question 5

What causes a decrease in the Earth’s temperature?

Answer 5

• At night, radiation is emitted by the atmosphere, clouds and surface
• This causes a decrease in the local temperature

Question 6

Converging (Convex) Lens

Answer 6

Causes parallel rays of light to be brought together (converge) at the principle focus - lens bulges outwards in the middle

Question 7

Diverging (Concave) Lens

Answer 7

Causes parallel rays of light to spread out (diverge) - Lens caves inwards

Question 8

What’s the difference between a real and virtual image?

Answer 8

• Real image can be projected onto a screen (virtual can’t)
• Virtual image appears to come from behind the lens

Question 9

How can the power of a lens be increased?

Answer 9

• increase its curvature

Question 10

What type of image do Diverging and Converging lenses produce?

Answer 10

Diverging (concave) - Virtual
Converging (convex) - Virtual or Real