Free Printable Physics Unit 9 Test

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Physics Unit 9 Test

Total questions: 40

Worksheet time: 59mins

Name

Class

Date

De-Broglie waves are associated with

Moving charged particles only

Moving neutral particles only

Accelerated charged particle

All particles in motion

Stopping potential for photoelectrons

Does not depend on the frequency of the incident light

Does not depend upon the nature of the cathode material

Depends on both the frequency of the incident light and nature of the cathode material

Depends upon the intensity of the incident light

The slope of the stopping potential versus ‘frequency graph for photoelectric effect is equal to

h/e

In photoelectric effect if the intensity of light is doubled then maximum kinetic energy of photoelectrons will become

Double

Half

Four-time

No change

In a semiconductor diode, the barrier offers opposition to only

Majority carries in both regions

Free electron in the n-regions

Minority carries in both regions

Holes in the p-regions

Which of the following is the correct statement?

No photo electronic emission takes place if the frequency of radiation however intense it may be is less than a certain critical value called threshold frequency

Threshold frequency depends upon the nature of the metal surface

The maximum energy of a photoelectron is a function of frequency rather than intensity of radiation

All of the above

A photon of wavelength 900nm behaves like a particle of mass

5.53 × 10^-36kg

0 kg

2.46 × 10^-36kg

1.84 × 10^-44kg

The curves (A), (B), (C) and (D) show the variation between the applied potential difference (V) and the photoelectric current (I), at two different intensities of light (I1 > I2). In which figure is the correct variation shown

The stopping potential in an experiment on the photoelectric effect is 1.5 V. What is the maximum kinetic energy of the photoelectrons emitted?

1.5 eV

3 eV

4.5 eV

6 eV

10.

If K.E. of free electron is doubled, its de Broglie wavelength will change by factor

$\frac{1}{\sqrt[]{2}}$

$\sqrt[]{2}$

$\frac{1}{2}$

11.

A proton, a neutron, an electron and an a-particle have same energy. Then their de Broglie wavelengths compare as

λ_p = λ_n > λ_e > λ_α

λ_α < λ_p = λ_n < λ_e

λ_e < λ_p = λ_n > λ_α

λ_e = λ_p = λ_n = λ_α

12.

The figure shows threshold frequencies fo for two different metallic surfaces A and B. The work function of A, as compared to that of B is

Less

Equal

Nothing can be said

13.

The de Broglie wavelength of a gas molecule at a temperature T K is:

$\frac{h}{\sqrt[]{3mKT}}$

$\frac{h}{3mKT}$

$\frac{h}{\sqrt[]{2mKT}}$

$\sqrt[]{2mKT}$

14.

When the AC input frequency of a half wave rectifier is 60Hz then the ripple frequency at output becomes .

50 Hz

60 Hz

100 Hz

120 Hz

15.

The basic purpose of filter is to

Minimize variations in ac input signal

Suppress harmonics in rectified output

Remove ripples from the rectified output

Stabilize dc output voltage

16.

Which one is reverse-biased?

17.

A 5-watt LED bulb converts 80% of the power into light photons of wavelength 660 nm. What is the number of photons emitted from the bulb in one second?

5.8 x 10³⁴

7.5 x 10¹⁸

6.6 x 10⁷

1.3 x 10¹⁹

18.

Compton shift is maximum at

90^o

0^o

180^o

None

19.

Which of the following figure represents the variation of particle momentum and the associated de-Broglie wavelength?

20.

Minimum energy required for pair production is:

939 MeV

942 MeV

1.02 MeV

0.51 MeV

21.

In Compton scattering process, the incident x-radiation is scattered at an angle 60°.

The wave length of scattered radiation is 0.22 A^o. The wavelength of incident radiation in A^o (Take $\frac{h}{m_oc}=0.024A^o$ )

0.508

0.408

0.232

0.208

22.

De-Broglie wavelength associated with electron in n = 4 level is

Half of the de-Broglie wavelength of electron in ground state

Four time of the de-Broglie wavelength of electron in ground state

1/4th of the de-Broglie wavelength of electron in ground state

Two times of the de-Broglie wavelength of electron in ground state

23.

There are n₁ photons of frequency f₁ in beam of light. In an equally energetic beam, there are n₂ photons of frequency f₂ then the correct relation is

$\frac{n_1}{n_2}=1$

$\frac{n_1}{n_2}=\frac{f_2}{f_1}$

$\frac{n_1}{n_2}=\frac{f_1}{f_2}$

$\frac{n_1}{n_2}=\frac{f_1^2}{f_2^2}$

24.

If E₁, E₂, E₃ are the respective kinetic energies of an electron, an alpha-particle and

a proton, each having the same de-Broglie wavelength then

E₁ > E₃ > E₂

E₂ > E₃ > E₁

E₁ > E₂ > E₃

E₁ = E₂ = E₃

25.

In the given figure the current through the resistor is practically.

5 A

2 A

Zero

1 A

26.

The de-Broglie wavelength of a particle accelerated with 150-volt potential is 10^-10m. If it is accelerated by 600 volts p.d., its wavelength will be

0.25 Å

0.5 Å

1.5 Å

2 Å

27.

A graph is plotted between energy of photons and their frequency and found to be a straight line in which “E” was along Y-axis and f along x-axis then the slope of this curve represents

Momentum

Plank’s constant

Wavelength

None

28.

In photo electric effect, anode is at high potential and cathode is at low potential. If potential difference between them is increased the photo electric current.

Also increases

Remain same

Decreases

None of these

29.

Threshold wavelength for metal having work function $\Phi^o$ is $\lambda$ . What is threshold wavelength for metal having work function $2\Phi^o$ is

$\frac{\lambda}{2}$

$4\lambda$

$2\lambda$

$\frac{\lambda}{4}$

30.

Light of frequency 1.5 times the threshold frequency is incident on a photo sensitive material. If the frequency is halved and intensity is doubled the photo electric current becomes

Four times

Double

Half

Zero

31.

Compton effect establishes

Wave nature of photon

Dual nature of photon

Particle nature of photon

Electromagnetic nature of photon

32.

Pair production cannot take place in vacuum because

Mass is not conserved

Momentum is not conserved

Energy is not conserved

Charge is not conserved

33.

During the half wave rectification, when diode is reverse biased the voltage drop across load resistance is

Maximum

Three times of maximum value

Half of maximum

Zero

34.

In the diagram, the input is across the terminals A and C and the output is across the terminals B and D, then the output is:

Zero

Same as input

Full wave rectifier

Half wave rectifier

35.

The resistance of a reverse biased PN-junction diode is about:

1 ohm

10³ ohm

10² ohm

10⁶ ohm

36.

The approximate wavelength of a photon of energy 2.48 eV is:

500 A

2000 A

5000 A

1000 A

37.

The photoelectric threshold wavelength of a certain metal is 3000 Å. If the radiation of 2000 Å is incident on the metal:

Electrons will be emitted

Positrons will be emitted

Protons will be emitted

Electrons will not be emitted

38.

The stopping potential for electrons ejected by 6.8xl0¹⁴ Hz electromagnetic radiation incident on a certain sample is 1.8 V. The kinetic energy of the most energetic electrons ejected and the work function of the sample, respectively, are:

1.8 eV, 2.8 eV

1.8eV, 1.0 eV

1.8 eV, 4.6 eV

2.8 eV, 1.0 eV

39.

When a point source of light is at a distance of one metre from a photocell, the cut off voltage is found to be V. If the same source is placed at 2 m distance from photocell, the cut off voltage will be:

V/4

V/2

$\frac{V}{\sqrt[]{2}}$

40.

In a photoelectric emission experiment using light of a certain frequency, the maximum kinetic energy E_k of the emitted photoelectrons is measured.

Which graph represents the way in which E_k depends on the intensity I of the light?

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Physics Unit 9 Test

Total questions: 40

Worksheet time: 59mins

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