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Blackbody

Total questions: 20

Worksheet time: 30mins

Name
Class
Date
1.

A hot metal radiates strongly at wavelength 600 nm. What is the temperature of the metal?

a)

2138 K

b)

4830K

c)

4230 K

d)

1290 K

2.

The energy produced by green light of wavelength 500 nm is

a)

1.00 x 10-10 J

b)

1.10 x 10-14 J

c)

3.98 x 10-19 J

d)

4.42 x 10-36J

3.

A sphere of surface area 2.0 m2 and at temperature 800 K is assumed to be a blackbody. What is the power radiated by the sphere?

a)

144 kW

b)

96 kW

c)

46 kW

d)

16 kW

4.

Which of the following statements is NOT TRUE concerning a blackbody

a)

It absorbs radiation of all wavelengths that fall on it

b)

It is a best emitter radiation

c)

It's radiation is also known as cavity radiation

d)

It reflects some radiation that falls on it

5.

A sun of radius 7.0 x 108 m and a surface temperature of 5800 K is assumed to be a blackbody. What is the rate of energy radiated by the sun?

a)

3.95 x 1026 W

b)

9.90 x 1025 W

c)

3.00 x 1015 W

d)

3.14 x 1025 W

6.

Choose the correct statement of an ideal blackbody

a)

Emits 100% of the light it generates, but cannot absorb its own radiation

b)

Absorbs half of the light incident upon it and emits half of the radiation it generates

c)

Absorbs all light incident on it, or emits all of the radiation it generates

d)

Absorbs 100% of the light incident upon it, but cannot emit light of its own

7.

One of the colours below is associated with the lowest temperature. Which one?

a)

red

b)

blue

c)

green

d)

orange

8.

For a perfect blackbody, the peak radiation intensity emitted by the body is

a)

dependent on the radiation that falls on the blackbody

b)

characteristic of the temperature of the blackbody

c)

always varying for a given temperature

d)

the same regardless of the temperature of the blackbody

9.

A light source is found to be emitting electromagnetic radiation with a frequency of 1015 Hz. Calculate the temperature of the source

a)

4560 K

b)

6540 K

c)

7320 K

d)

9660 K

10.

A spherical blackbody of radius 12 cm is maintained at a temperature of 427 ⁰C. Find the power radiated by the blackbody.

a)

2463 W

b)

3456 W

c)

4323 W

d)

4664 W

11.

An object with surface area of 2.3 m2 is placed in a room temperature of 50 ⁰C. If the object is at 75 ⁰C and emissivity, e = 0.80, calculate the heat loss of the object through radiation

a)

387 W

b)

397 W

c)

687 W

d)

697 W

12.

The human eye is most sensitive to the light with a wavelength, λ = 560 nm. Determine the temperature a blackbody would radiate most intensely at this wavelength.

a)

2536 K

b)

3542 k

c)

4325 K

d)

5338 K

13.

Determine the energy range of photons for the visible spectrum with wavelength range from 410 nm to 750 nm.

a)

2.65 x 10-16 J – 4.9 x 10-16 J

b)

2.65 x 10-19 J – 4.9 x 10-19 J

c)

2.65 x 10-21 J – 4.9 x 10-21 J

d)

2.65 x 10-23 J – 4.9 x 10-23 J

14.

The surface of the sun can be treated as a blackbody of temperature about 5800 K. What is the peak-intensity wavelength, λm?

a)

5.0 x 10-3 m

b)

5.0 x 10-5 m

c)

5.0 x 10-7 m

d)

5.0 x 10-9 m

15.

A student had a skin temperature of 33 ˚C and was in a room where the walls were at 29 ˚C. If the emissivity is 1 and the body surface area is 1.5 m2, determine the rate of heat loss due to radiation.

a)

38 w

b)

42 w

c)

48 w

d)

52 w

16.

Cauculate the deBroglie wavelength of a 0.05 g projectile fired at 180 ms-1

a)

2.4 x 10-27 m

b)

1.8 x 10-30 m

c)

7.4 x 10-32 m

d)

7.4 x 10-35 m

17.

Choose the correct statement for photon

a)

Photon is a quantum of electromagnetic wave

b)

Photon is a particle with a positive charge

c)

Photon is a particle with a negative charge

d)

Photon is the electron produced when light is incident on a metal's surface

18.

Identify the physical phenomena that cannot be described by the wave theory of light

a)

Diffraction

b)

Polarization

c)

Interference

d)

Photoelectric effect

19.

An electron has a deBroglie's wavelength of 2.9 x 10-3 m. Find its speed.

a)

2.3 x 10-3 ms-1

b)

2.5 x 10-1 ms-1

c)

1.4 x 10-4 ms-1

d)

1.6 x 10-3 ms-1

20.

What happens to the deBroglie's wavelength of an electron if its momentum is doubled?

a)

The wavelength decreases by a factor of 2

b)

The wavelength increases by a factor of 2

c)

The wavelength decreases by a factor of 3

d)

The wavelength decreases by a factor of 4