Quantum mechanics Quiz 1

Question 1

Refer the diagram given below. If the power of the source is $$P$$ watts, calculate the ratio of the intensities at both the mirrors of side $$a$$, consider the power of the beam to be constant throughout. $$ \ $$ <img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/e4746412-9c82-4686-9bb8-171bd2de34368732758874295395832.png"/>

Accepted Answer

$$\sqrt{3}:4$$

Answer

$$4:\sqrt{3}$$

Answer

$$3:4$$

Answer

$$4:3$$

Question 2

A hydrogen like atom can absorb an energy of $$690	ext{ eV}\$$. The emission spectrum is shown in the diagram below. Find the minimum wavelength of the emitted radiation. $$ \ $$ <img  src="https://cmds-vedantu.s3.ap-southeast-1.amazonaws.com/prod/question-sets/37a50aa2-61b8-4a3d-aad8-17ac5d3719c77715836466162104229.png"/>

Accepted Answer

$$\dfrac{9}{108.8{Z}^{2}}$$

Answer

$$\dfrac{9}{100.8{Z}^{2}}$$

Answer

$$\dfrac{13.6}{108.8{Z}^{2}}$$

Answer

None of the above

Question 3

For a hypothetical hydrogen like atom the difference between the energies in ninth and eighth orbitals  is $$8	ext{ eV}\$$. What is the atomic number of this atom?

Accepted Answer

$$13$$

Answer

$$10$$

Answer

$$12$$

Answer

$$14$$

Question 4

A photocell is made up of a certain material such that when a monochromatic light of wavelength  $$6000	ext{ }\overset{\circ }{\mathop{	ext{A}}}\,$$ is incident on it the maximum velocity reached by the emitted photoelectrons is $$v$$ , but when a monochromatic light of wavelength $$8000	ext{ }\overset{\circ }{\mathop{	ext{A}}}\,$$ is incident on it the maximum velocity of the emitted photoelectron is $$2v$$ . Find the threshold wavelength of the material.

Accepted Answer

$$5538.46	ext{ }\overset{\circ }{\mathop{	ext{A}}}\,$$

Answer

$$5438.49	ext{ }\overset{\circ }{\mathop{	ext{A}}}\,$$

Answer

$$5439.48	ext{ }\overset{\circ }{\mathop{	ext{A}}}\,$$

Answer

$$5539.47	ext{ }\overset{\circ }{\mathop{	ext{A}}}\,$$

Question 5

A photocell is operating in saturation mode with a photocurrent of $$8	ext{ }\mu 	ext{A}$$ . If a monochromatic light of wavelength $$4000	ext{ }\overset{\circ}{\mathop{	ext{A}}}\,$$ and power $$4	ext{ mW}$$ is incident on the photocell, determine the efficiency of the photocell.

Accepted Answer

0.061%

Answer

8.1%

Answer

81%

Answer

0.61%