Light of wavelength 4000 A ∘ and intensity 100 Wm - 2 is incident on a plate of threshold frequency 5 . 5 × 10 14 Hz . Find the maximum kinetic energy of photoelectrons and number of photons incident per m 2 per second.

K . E = h v - h v ∘ K . E = h c l - h ( 5 . 5 × 10 14 ) K . E = 6 . 626 × 10 - 34 3 × 10 8 4000 × 10 - 10 - 5 . 5 × 10 14 J K . E = 1 . 32 × 10 - 19 J Energy = 100 J ⇒ nhc l = 100 ⇒ n × 6 . 626 × 10 - 34 × 3 × 10 8 4000 × 10 - 10 = 100 ⇒ n = 2 . 02 × 10 20 m 2

MEDIUM

12th West Bengal Board

IMPORTANT

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The work function of caesium is $2.14 eV$ . Find the wavelength of the incident light if the photocurrent is brought to zero by a stopping potential of $0.60 V$ .

Important Questions on Photoelectric Emission and Production and Properties of X-Rays

EASY

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 19 - Photoelectric Emission and Production and Properties of X-Rays>EXERCISE 19>Q 13

For the photoelectric effect in a metal, Figure shows the plot of cut-off voltage versus frequency of incident radiation. Determine the threshold frequency,

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MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 19 - Photoelectric Emission and Production and Properties of X-Rays>EXERCISE 19>Q 13

For photoelectric effect in a metal, Fig. $19.14$ shows the plot of cut-off voltage versus frequency of incident radiation. Determine work function of the given metal.

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EASY

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 19 - Photoelectric Emission and Production and Properties of X-Rays>EXERCISE 19>Q 14

By how much the stopping potential for a given photosensitive surface go up if the frequency of the incident radiations were to be increased from

4 \times 10^{15} Hz

8 \times 10^{15} Hz

? Given

: h = 6.4 \times 10^{- 34} Js, e = 1.6 \times 10^{- 19} C

and

c = 3 \times 10^{8} m / s

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 19 - Photoelectric Emission and Production and Properties of X-Rays>EXERCISE 19>Q 15

Light of wavelength

4000 \overset{\circ}{A}

and intensity

100 {Wm}^{- 2}

is incident on a plate of threshold frequency

5.5 \times 10^{14} Hz

. Find the maximum kinetic energy of photoelectrons and number of photons incident per

m^{2}

per second.

EASY

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 19 - Photoelectric Emission and Production and Properties of X-Rays>EXERCISE 19>Q 16

What should be the minimum potential difference between the ends of a coolidge tube, to produce X-rays of wavelength

0.8 \vec{A}

?
Given:

h = 6.62 \times 10^{- 34} Js, e = 1.60 \times 10^{- 19}

C and

c = 3 \times 10^{8} m / s

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 19 - Photoelectric Emission and Production and Properties of X-Rays>EXERCISE 19>Q 17

Calculate the minimum wavelength of X-rays produced by an X -ray tube operating at

30 kV . [h = 6.6 \times 10^{- 27} erg . c]

EASY

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 19 - Photoelectric Emission and Production and Properties of X-Rays>EXERCISE 19>Q 18

The potential difference across an X -ray tube is

12.4 kV

and the current through the filament is

2 mA .

Calculate the number of electrons striking per second on the anode

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 19 - Photoelectric Emission and Production and Properties of X-Rays>EXERCISE 19>Q 18

The potential difference across an X -ray tube is

12.4 kV

and the current through the filament is

2 mA .

Calculate the speed with which the electron strikes the target

The work function of caesium is 2.14eV. Find the wavelength of the incident light if the photocurrent is brought to zero by a stopping potential of 0.60 V.

Important Questions on Photoelectric Emission and Production and Properties of X-Rays

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The work function of caesium is $2.14 eV$ . Find the wavelength of the incident light if the photocurrent is brought to zero by a stopping potential of $0.60 V$ .