List of top Physics Questions

An EM wave of frequency \( 5 \times 10^9 \, Hz \) falls normally on a rectangular slit of width \( 3 \, cm \). What is the total angular width of the central maxima?

An open pipe is in second harmonic with frequency \( f_1 \). One end of the tube is closed and frequency is increased to \( f_2 \) and it resonates again with nth harmonic. For what value of \( n \), the ratio of \( \frac{f_1}{f_2} \) is \( \frac{4}{5} \)?

Across the \( 220 \, V \) source of internal resistance \( 20\Omega \), how many lamps of \( 40 \, W, 100 \, V \) can be connected in parallel so that all the lamps may glow with full brightness.

If the radius of earth were to shrink by two percent, its mass remaining the same, the acceleration due to gravity on the earth's surface would

When a dielectric slab of dielectric constant \( k = 2 \) is used to fill the space between the plates of a parallel plate capacitor, the capacitance of the capacitor is found to be \( 20 \mu F \). What will be the capacitance when the slab is replaced with air?

The focal lengths of the objective and eyepiece of a compound microscope are \( 1 \, \text{cm} \) and \( 10 \, \text{cm} \) respectively. Length of the tube is \( 25 \, \text{cm} \). If the final image is formed at infinity, the magnifying power of the microscope is:

The resistance of the conductor is \( \sqrt{3}\Omega \) the angle made by the V-I graph with the voltage axis is \( \theta \)

In which of the following circuit do we find the current and voltage in phase?

A body weighing 125 kg just slides down a rough inclined plane that rises 1 m in every 2 m. What is the coefficient of friction?

A gun is used to fire a bullet at an angle of \( 30^\circ \) and at \( 60^\circ \) respectively. The ratios of heights and ranges reached by the bullet are

An ideal gas is expanding such that \( PT^2 = \text{constant} \). The coefficient of volume expansion of the gas is

Diamond is considered as an insulator because

A galvanometer of \( 50\Omega \) resistance is converted into an ammeter using a shunt resistance of \( 10\Omega \). If the same resistance is used to convert the same galvanometer into a voltmeter, what would be the ratio of the resistance of the ammeter to the resistance of the voltmeter?

A ray of light is travelling from glass of refractive index \( \frac{3}{2} \) to water of refractive index \( \frac{4}{3} \). What is the minimum angle of incidence for which no light enters into the water?

A monoatomic ideal gas, initially at temperature \( T_1 \), is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature \( T_2 \) by releasing the piston suddenly. If \( L \) and \( 2L \) are the lengths of the gas column before and after expansion respectively, then \( \frac{T_1}{T_2} \) is

The nucleus of oxygen atom contains 8 protons and 8 neutrons. What is the mass defect in amu? [Given Mass of proton = 1.00727 amu Mass of neutron = 1.00866 amu and the mass of oxygen nucleus = 15.99053 amu.]

Ten cells, each having internal resistance \( 1\Omega \) and emf \( 1.5 \, V \) are connected in series. But unknowingly 3 cells are connected wrongly in series. The effective internal resistance and emf of the series combination are respectively:

Time period of oscillation of a mass suspended from a spring is \( T \). If the spring is cut into four equal parts and the same mass is suspended from one of the parts, the fractional change in time period is

The square of resultant of two equal electric field vectors is three times their product. Angle between them is

Rods \( A \) and \( B \) have their lengths in the ratio \( 1 : 2 \). Their thermal conductivities are \( K_1 \) and \( K_2 \) respectively. The temperatures at the ends of each rod are \( T_1 \) and \( T_2 \). If the rate of flow of heat through the rods is equal, the ratio of area of cross section of \( A \) to that of \( B \) is

The heat required to increase the temperature of 4 moles of a mono-atomic ideal gas from \( 273^\circ C \) to \( 473^\circ C \) at constant volume is

The wire made of Phosphor bronze is used as the suspension strip in the moving coil galvanometer, because:

Which physical quantity has the unit joule tesla?

Fusion reaction is more energetic than fission reaction because

The ratio of the number of turns of the primary coil to the secondary coil of an ideal transformer is \( 5 : 1 \). The primary is connected to \( 220 \, V \) supply. What is the output power of the transformer if the output resistance is \( 11 \Omega \)?