1
MHT CET 2021 20th September Evening Shift
+1
-0

What is the additional energy that should be supplied to a moving electron to reduce its de Broglie wavelength from $$1 \mathrm{~nm}$$ to $$0.5 \mathrm{~nm}$$ ?

A
Four times its initial energy.
B
Five times its initial energy.
C
Two times its initial energy.
D
Three times its initial energy.
2
MHT CET 2021 20th September Evening Shift
+1
-0

Photoelectrons are emitted when photons of energy $$4.2 ~\mathrm{eV}$$ are incident on a photosensitive metallic sphere of radius $$10 \mathrm{~cm}$$ and work function $$2.4 ~\mathrm{eV}$$. The number of photoelectrons emitted before the emission is stopped is

$$\left[\frac{1}{4 \pi \epsilon_0}=9 \times 10^9\right.$$ SI unit; $$\left.\mathrm{e}=1.6 \times 10^{-19} \mathrm{C}\right]$$

A
$$1.25 \times 10^6$$
B
$$1.25 \times 10^2$$
C
$$1.25 \times 10^8$$
D
$$1.25 \times 10^4$$
3
MHT CET 2021 20th September Morning Shift
+1
-0

When light of wavelength '$$\lambda$$' is incident on a photosensitive surface, photons of power 'P' are emitted. The number of photon 'n' emitted in time 't' is [h = Planck's constant, c = velocity of light in vacuum]

A
$$\mathrm{\frac{hc}{p\lambda t}}$$
B
$$\mathrm{\frac{P\lambda}{htc}}$$
C
$$\mathrm{\frac{P\lambda t}{hc}}$$
D
$$\mathrm{\frac{hP}{\lambda tc}}$$
4
MHT CET 2021 20th September Morning Shift
+1
-0

When a photosensitive surface is irradiated by light of wavelengths '$$\lambda_1$$' and '$$\lambda_2$$', kinetic energies of emitted photoelectrons are 'E$$_1$$' and 'E$$_2$$' respectively. The work function of photosensitive surface is

A
$$\frac{\left(\lambda_1 E_1-\lambda_2 E_2\right)}{\left(\lambda_2-\lambda_1\right)}$$
B
$$\frac{\left(\lambda_1 \mathrm{E}_1+\lambda_2 \mathrm{E}_2\right)}{\left(\lambda_2-\lambda_1\right)}$$
C
$$\frac{\left(\lambda_1 \mathrm{E}_2-\lambda_2 \mathrm{E}_1\right)}{\left(\lambda_2-\lambda_1\right)}$$
D
$$\frac{\left(\lambda_1 E_2+\lambda_2 E_1\right)}{\left(\lambda_2-\lambda_1\right)}$$
MHT CET Subjects
Physics
Mechanics
Optics
Electromagnetism
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
Calculus
Coordinate Geometry
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