Hertz's Observations

Q.

What are the properties of matter waves?

Q. A particular hydrogen like ion emits radiation of frequency $2.92\times {10}^{15}\text{Hz}$ when it makes transition from $n=3$ to $n=1$. The frequency (in $\text{Hz}$) of radiation emitted, in transition from $n=2$ to $n=1$, will be:

1. $2.46\times {10}^{15}$
2. $4.38\times {10}^{15}$
3. $0.44\times {10}^{15}$
4. $6.57\times {10}^{15}$

Q. Three discs, a, b, c having radii 2m, 4m, 6m respectively are coated with carbon black on their outer surface the wavelength corresponding to maximum intensity are 300, 400, 500nm respectively the power radiated by them are Q_A, Q_B, ​​​​​​, Q_c
Opts-
Q_a is max
Q_bis max
Q_c is max
Q_a=Q_b=Q_c

Q. How can we distinguish between longitudinal and transverse waves?

1. By interference
2. By reflection
3. By polarization
4. By doppler's effect

Q.

Why de Broglie waves are non-electromagnetic?

Q.

the most incomprehensible thing about world is that it is most comprehensible meaning of this sentence by einstein

Q.

Explain the working of photoemissive cells. Write any two applications of photoelectric cells.

Q.

The work function for a certain metal is 4.2 eV. Will this metal give photoelectric emission for incident radiation of wavelength 330 nm?

Q. A monochromatic light of wavelength x is incident on an isolated metallic sphere of radius a. The threshold wavelength is x1 which is larger than x. Find the number of photoelectrons emitted before the emission of photoelectrons stop.

Q.

A monitor is also called a _____?

Q. In a double slit experiment, two incoherent sources are placed at the two slits. The intensity of sources at $S_1$ is $I_0$ and that at $S_2$ is $3I_0$. Identity the correct statement.

1. Destructive interference will result at central position on screen.
2. The resultant intensity at centre of screen will be $3I_0$.
3. The resultant intensity at any point on screen will be $4I_0$.
4. The resultant intensity at any point on screen will be $2I_0$.

Q. The spectrum obtained from a sodium vapour lamp is an example of -

1. band spectrum
2. continuous spectrum
3. emission spectrum
4. absorption spectrum

Q. Davission and Germer experiment proved

1. Neither (a) nor (b)

2. Wave nature of light

3. Both (a) and (b)
4. Particle nature of light

Q. Best physics reference books for JEE.

Q. If light of wavelength 412.5 nm is incident on each of the metals given below, which ones will show photoelectric emission and why ?

$\begin{array}{cc}\text{Metal}& \text{Work Function (eV)}\\ \text{Na}& 1.92\\ \text{K}& 2.15\\ \text{Ca}& 3.20\\ \text{Mo}& 4.17\end{array}$

Q.

Light of wavelength${\lambda }_1=340nm$ and ${\lambda }_2=540nm$ are incident on a metallic surface. If the ratio of the speed of the electrons ejected is $2$. The work function of the metal is.

1. $1eV$

2. $1.85eV$

3. $1.5eV$

4. $2eV$

Q. In a historical experiment to determine Planck's constant, a metal surface was irradiated with light of different wavelengths. The emitted photoelectric energies were measured by applying a stopping potential. The relevant data for the wavelength ($\lambda$) of incident light at the corresponding stopping potential ($V_0$) are given below:

$\lambda \left(\mu m\right)$	$V_0$ (Volt)
$0.3$	$2.0$
$0.4$	$1.0$
$0.5$	$0.4$

Given, $c=3\times {10}^{8}m{s}^{-1}$ and $e=1.6\times {10}^{-19}C$, Planck's constant (in units of $J-s$) from such an experiment is

1. $6.0\times {10}^{-34}$
2. $6.4\times {10}^{-34}$
3. $6.6\times {10}^{-34}$
4. $6.8\times {10}^{-34}$

Q. Using photon picture of light, show how Einstein's photoelectric equation can be established. Write two features of photoelectric effect which cannot be explained by wave theory.

Q.

Teh index of refraction of fused quartz is 1.472 for light of wavelength 400 nm and is 1.452 for hight of wavelength 760 nm. Find the speeds of ight of these wavelengths in fused quartz.

Q. If an electromagnetic wave propagating through vacuum is described by Ey = E0 sin (kx t);Bz = B0 sin (kx t), then what is the relation between E and B ?

Q.

Select the right option in the following

1. Maxwell provides compelling theoretical evidence that light is a transverse wave.

2. Thomas Young experimentally proved the wave behavior of light and Huygens assumption.

3. Christiaan Huygens, a contemporary of Newton, established the wave theory of light by assuming that light waves were transverse.

4. All the statements given above correctly answer the question “what is light”.

Q. The maximum number of photons emitted by a hydrogen atom , if the atom is excited to the states with principal quantum number four is-

1. $1$
2. $4$
3. $6$
4. $2$

Q.

Electrons of mass m with de Broglie wavelength lambda fall on the target in an X-ray tube. The cut-off wavelength λ₀ of the emitted X-rays is:

1. λ₀ = λ

2. λ₀ = 2mcλ²/h

3. λ₀ = 2h/mc

4. λ₀ = 2m²c²λ³/h²

Q. Which source is associated with a line emission spectrum?

1. Electric fire
2. Neon street sign
3. Red traffic light
4. Sun

Q.

What is Schrodinger’s cat?

Q. 59. What considration led de broglie to suggedt that material partical can also show wave property??

Q.

In the Coolidge tube, the cathode is heated till electrons are thermionically ejected from the filament. We could also use photoelectric effect on the cathode plate to obtain these electrons for x-ray generation.

1. True

2. False

Q. Why light is called electromagnetic wave

Q.

During the photo electric effects electrons get ejected due to photons.if this process continues then at a certain point of time all the electrons should be ejected out.and thus even could affect the stability of the metal itself.but in real life it dose not happen.why?

Q. In hydrogen spectrum the shortest wavelength in the Balmer series is ${\lambda }_0$. The largest wavelength in Lyman series for helium ion, is

1. $\frac{5}{3}{\lambda }_0$
2. $12{\lambda }_0$
3. $\frac{12}{5}{\lambda }_0$
4. $\frac{{\lambda }_0}{12}$