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A-Level CAIE Physics 25 1 Standard Candles Question Bank

Practice A-Level CAIE Physics 25 1 Standard Candles questions by syllabus topic with past-paper context, marks, difficulty and question previews on Eduninja.

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Question 3

3

2 marks

Question 3(c)

3(c)

The radiant flux intensity of the radiation from the star in (b) is \(2.52 \times 10^{-8} \mathrm{Wm}^{-2}\) when observed at a distance of \(4.16 \times 10^{16} \mathrm{~m}\) from the star.

structured2 marks

Question 3(c)(i)

3(c)(i)

Calculate the luminosity of the star. Give a unit with your answer. luminosity = unit

Mediumstructured2 marks

Answer

\(L=F \times 4 \pi d^{2}\) C1 \[ \begin{aligned} L =2.52 \times 10^{-8} \times 4 \pi \times\left(4.16 \times 10^{16}\right)^{2} =5.48 \times 10^{26} \mathrm{~W} \end{aligned} \] A1

Question 10

10

3 marks

Question 10(a)

10(a)

A student observes different stars from the Earth. Give two reasons why some stars appear brighter than others. 1 2

Mediumstructured2 marks

Answer

brighter star could be closer (to Earth) B1 brighter star could have a greater luminosity (in the visible wavelengths) B1

Question 10(b)

10(b)

State what is meant by a standard candle.

Easystructured1 marks

Answer

object with known luminosity B1

Question 9

9

3 marks

Question 9(a)

9(a)

State what is meant by the luminosity of a star.

Easystructured1 marks

Answer

total power of radiation emitted (by the star) B1

Question 9(b)

9(b)

A star in the constellation Canis Major is a distance of \(8.14 \times 10^{16} \mathrm{~m}\) from the Earth and has a luminosity of \(9.86 \times 10^{27} \mathrm{~W}\). The surface temperature of the star is 9830 K .

structured2 marks

Question 9(b)(i)

9(b)(i)

Calculate the radiant flux intensity of the radiation from the star observed from the Earth. Give a unit with your answer. radiant flux intensity = unit

Mediumstructured2 marks

Answer

\(F=L /\left(4 \pi d^{2}\right)\) C1 \[ \begin{aligned} =9.86 \times 10^{27} /\left[4 \pi \times\left(8.14 \times 10^{16}\right)^{2}\right] =1.18 \times 10^{-7} \mathrm{Wm}^{-2} \end{aligned} \] A1

Question 10

10

2 marks

Question 10(a)

10(a)

The Sun has a surface temperature of 5780 K . The luminosity of the Sun is \(3.85 \times 10^{26} \mathrm{~W}\).

structured2 marks

Question 10(a)(ii)

10(a)(ii)

The Earth is a distance of \(1.50 \times 10^{11} \mathrm{~m}\) from the Sun. Calculate the radiant flux intensity F of the radiation from the Sun at a distance of \(1.50 \times 10^{11} \mathrm{~m}\). Give a unit with your answer. unit

Mediumstructured2 marks

Answer

\[ \begin{aligned} F =L / 4 \pi d^{2} =\left(3.85 \times 10^{26}\right) /\left(4 \pi \times\left(1.50 \times 10^{11}\right)^{2}\right) \end{aligned} \] C1 \(=1.36 \times 10^{3} \mathrm{~W} \mathrm{~m}^{-2}\) A1

Question 10

10

7 marks

Question 10(a)

10(a)

5 marks

Question 10(a)(i)

10(a)(i)

State what is meant by the luminosity of a star.

Easystructured2 marks

Answer

total power B1 power radiated (by the star) B1

Question 10(a)(ii)

10(a)(ii)

Explain how a standard candle in a distant galaxy can be used to determine the distance of the galaxy from an observer.

Mediumstructured3 marks

Answer

standard candle has known luminosity B1 radiant flux intensity measured by observer B1 (distance calculated using) \(F=L / 4 \pi d^{2}\) B1

Question 10(b)

10(b)

The Sun has a radius of \(6.96 \times 10^{8} \mathrm{~m}\) and a surface temperature of 5780 K . Light from the Sun is observed to have a peak intensity at a wavelength of 501 nm .

structured2 marks

Question 10(b)(i)

10(b)(i)

Calculate the luminosity of the Sun. Give a unit with your answer. unit

Mediumstructured2 marks

Answer

luminosity \(=4 \pi \sigma r^{2} T^{4}\) \[ =4 \pi \times 5.67 \times 10^{-8} \times\left(6.96 \times 10^{8}\right)^{2} \times 5780^{4} \] C1 \(=3.85 \times 10^{26} \mathrm{~W}\) A1

Question 12

12

3 marks

Question 12(a)

12(a)

A star has a luminosity that is known to be \(4.8 \times 10^{29} \mathrm{~W}\). A scientist observing this star finds that the radiant flux intensity of light received on Earth from the star is \(2.6 \mathrm{nW} \mathrm{m}^{-2}\).

structured3 marks

Question 12(a)(i)

12(a)(i)

Name the term used to describe an astronomical object that has known luminosity.

Easystructured1 marks

Answer

standard candle B1

Question 12(a)(ii)

12(a)(ii)

Determine the distance of the star from Earth.

Mediumstructured2 marks

Answer

\(F=L / 4 \pi d^{2}\) C1 \(2.6 \times 10^{-9}=4.8 \times 10^{29} / 4 \pi d^{2}\) distance \(=3.8 \times 10^{18} \mathrm{~m}\) A1

Question 10

10

1 marks

Question 10(b)

10(b)

A cosmology student observes the electromagnetic radiation received from a star in a galaxy. The student uses Wien's law to estimate the surface temperature of the star, a standard candle to estimate the distance to the galaxy, and the Stefan-Boltzmann law to estimate the radius of the star. The student observes that the radiation from the star is redshifted.

structured1 marks

Question 10(b)(i)

10(b)(i)

State what is meant by a standard candle.

Easystructured1 marks

Answer

(astronomical) object of known luminosity B1

Question 10

10

2 marks

Question 10(b)

10(b)

A star of luminosity \(3.8 \times 10^{31} \mathrm{~W}\) is a distance of \(1.8 \times 10^{24} \mathrm{~m}\) from the Earth. Calculate the radiant flux intensity at the Earth of the radiation emitted by the star. radiant flux intensity = \(\mathrm{Wm}^{-2}\)

Mediumstructured2 marks

Answer

\(F=L /\left(4 \pi d^{2}\right)\) C1 \[ \begin{aligned} =\left(3.8 \times 10^{31}\right) /\left[4 \pi \times\left(1.8 \times 10^{24}\right)^{2}\right] =9.3 \times 10^{-19} \mathrm{~W} \mathrm{~m}^{-2} \end{aligned} \] A1

Question 10

10

2 marks

Question 10(b)

10(b)

A star of luminosity \(3.8 \times 10^{31} \mathrm{~W}\) is a distance of \(1.8 \times 10^{24} \mathrm{~m}\) from the Earth. Calculate the radiant flux intensity at the Earth of the radiation emitted by the star. radiant flux intensity = \(\mathrm{Wm}^{-2}\)

Mediumstructured2 marks

Answer

\(F=L /\left(4 \pi d^{2}\right)\) C1 \[ \begin{aligned} =\left(3.8 \times 10^{31}\right) /\left[4 \pi \times\left(1.8 \times 10^{24}\right)^{2}\right] =9.3 \times 10^{-19} \mathrm{~W} \mathrm{~m}^{-2} \end{aligned} \] A1

Question 12

12

3 marks

Question 12(a)

12(a)

State what is meant by luminosity of a star.

Easystructured1 marks

Answer

total power of radiation emitted (by the star) B1

Question 12(b)

12(b)

The luminosity of the Sun is \(3.83 \times 10^{26} \mathrm{~W}\). The distance between the Earth and the Sun is \(1.51 \times 10^{11} \mathrm{~m}\). Calculate the radiant flux intensity F of the Sun at the Earth. Give a unit with your answer.

Mediumstructured2 marks

Answer

\[ \begin{aligned} F=\frac{L}{4 \pi d^{2}} =\frac{3.83 \times 10^{26}}{4 \times \pi \times 1.51 \times 10^{112}} \end{aligned} \] C1 \(=1340 \mathrm{~W} \mathrm{~m}^{-2}\) A1