Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is

In biprism experiment, if $5^{\text {th }}$ bright band with wavelength $\lambda_1$ coincides with $6^{\text {th }}$ dark band with wavelength $\lambda_2$ then the ratio $\left(\lambda_1 / \lambda_2\right)$ is

Ordinary bodies P and Q radiate maximum energy with wavelength difference $3 \mu \mathrm{~m}$. The absolute temperature of body P is four times that of Q. The wavelength at which body Q radiates maximum energy is

A lead bullet moving with velocity ' V ' strikes a wall and stops. If $75 \%$ of its energy is converted into heat, then the increase in temperature is ( $\mathrm{s}=$ specific heat of lead, $\mathrm{J}=$ mechanical equivalent of heat)