Physics 2nd Paper CQ-Dhaka Board-2022

1. Ananya is conducting a photoelectric effect experiment by using light of wavelength $4.5 \times 10^{-7} \mathrm{~m}$ on ceisium metal plate. She achieved a stopping potential of $1.5 \mathrm{~V}$. Later she used a green light of wavelength $5.5 \times 10^{-7} \mathrm{~m}$. [Given that the mass of an electron is $9.1 \times 10^{-31} \mathrm{~kg}$ ].

2. A piece of ice of $0.07 \mathrm{~kg}$ at $0^{\circ} \mathrm{C}$ is dropped from a certain height. As a result, $55 \%$ of the potential energy is converted into heat and this heat melts the ice fully. After a while, the temperature of the melted water is raised to $5^{\circ} \mathrm{C}$. Given that specific latent heat of fusion of ice is $3.36 \times 10^{5} \mathrm{~J} \mathrm{~kg}^{-1}$ and specific heat of water is $4200 \mathrm{Jkg}^{-1} \mathrm{k}^{-1}$.

3. In figure, a sphere of mass $100 \mathrm{~g}$ carrying charge of $1 \mu \mathrm{C}$ at point $D$ is kept on the ground. Here $A B=A D=B D$ and $\angle A C B=90^{\circ}$. The whole system is kept vertically.

4. Each diode used in the circuit is identical. If $0.6 \mathrm{~V}$ potential difference is maintained in the two terminals of any of them then current changed $150 \mathrm{~mA}$ from $100 \mathrm{~mA}$. Again with the help of this bridge circuit when $A C$ signal is set to convert into DC signal, it is found that diod $\mathrm{D}_{4}$ is damaged.

5. In Young's double slit experiment a light of wavelength $5800 \mathrm{~A}$ is used. Later the double slit is replaced by a single slit of width $0.2 \mathrm{~mm}$.