MCQ
Threshold wavelength for photoelectric effect on sodium is $5000 \mathring A$. lts work function is
- A$15 \mathrm{~J}$
- B$16 \times 10^{-14} J$
- ✓$4 \times 10^{-19} J$
- D$4 \times 10^{-81} J$
✓
Answer
Correct option: C.
$4 \times 10^{-19} J$
$W_0=\frac{h c}{\lambda_0}=\frac{6.625 \times 10^{-34} \times 3 \times 10^8}{5000 \times 10^{-10}} \mathrm{~J}=4 \times 10^{-19} \mathrm{~J}$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
In a terrestrial telescope, the focal length of objective is $90 \mathrm{~cm}$, of inverting lens is $5 \mathrm{~cm}$ and of eye lens is $6 \mathrm{~cm}$. If the final image is at $30 \mathrm{~cm}$, then the magnification will be
→When a copper ball is heated, the largest percentage increase will occur in its
A tank is filled with water up to a height $H$. Water is allowed to come out of a hole $P$ in one of the walls at a depth $D$ below the surface of water. Express the horizontal distance $x$ in terms of $H$ and $D$
→When the amount of work done is $333 \mathrm{cal}$ and change in internal energy is $167 \mathrm{cal}$, then the heat supplied is
→There are two planets. The ratio of radius of the two planets is $K$ but ratio of acceleration due to gravity of both planets is $g$. What will be the ratio of their escape velocity
→A body of mass $m$ accelerates uniformly from rest to $v_1$ in time $t_1$. As a function of time $t$, the instantaneous power delivered to the body is
→At which of the following temperatures, the value of surface tension of water is minimum
Two conducting circular loops of radii $R_1$ and $R_2$ are placed in the same plane with their centres coinciding. If $R_1 \gg R_2$, the mutual inductance $M$ between them will be directly proportional to
→The graph which represents the relation between the total resistance $R$ of a multi range moving coil voltmeter and its full scale deflection $V$ is
→
If a magnetic substance is kept in a magnetic field, then which of the following is thrown out