ExamGOAL
Books
PreviousNext
3
MCQ (Single Correct Answer)

Consider a beam of electrons (each electron with energy $E_0$ ) incident on a metal surface kept in an evacuated chamber. Then,

A
no electrons will be emitted as only photons can emit electrons
B
electrons can be emitted but all with an energy, $E_0$
C
electrons can be emitted with any energy, with a maximum of $E_0-\phi$ ( $\phi$ is the work function)
D
electrons can be emitted with any energy, with a maximum of $E_0$
4
MCQ (Single Correct Answer)

Consider figure given below. Suppose the voltage applied to $A$ is increased. The diffracted beam will have the maximum at a value of $\theta$ that

A
will be larger than the earlier value
B
will be the same as the earlier value
C
will be less than the earlier value
D
will depend on the target
5
MCQ (Single Correct Answer)

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

A
$\lambda_p=\lambda_n>\lambda_e>\lambda_\alpha$
B
$\lambda_\alpha<\lambda_p=\lambda_n>\lambda_e$
C
$\lambda_e<\lambda_p=\lambda_n>\lambda_\alpha$
D
$\lambda_e=\lambda_p=\lambda_n=\lambda_\alpha$
6
MCQ (Single Correct Answer)

An electron is moving with an initial velocity $\mathbf{v}=v_0 \hat{\mathbf{i}}$ and is in a magnetic field $\mathbf{B}=B_0 \hat{\mathbf{j}}$. Then, it's de-Broglie wavelength

A
remains constant
B
increases with time
C
decreases with time
D
increases and decreases periodically
7
MCQ (Single Correct Answer)

An electron (mass $m$ ) with an initial velocity $\mathbf{v}=v_0 \mathbf{i}\left(v_0>0\right)$ is in an electric field $\mathbf{E}=-E_0 \hat{\mathbf{i}}\left(E_0=\right.$ constant $\left.>0\right)$. It's de-Broglie wavelength at time $t$ is given by

A
$\frac{\lambda_0}{\left(1+\frac{e E_0}{m} \frac{t}{v_0}\right)}$
B
$\lambda_0\left(1+\frac{e E_0 t}{m v_0}\right)$
C
$\lambda_0$
D
$\lambda_0 t$
PreviousNext