List of top Questions asked in KEAM

The half-life of a radioactive substance is 20 minutes. The time taken between 50% decay and 87.5% decay of the substance will be

An electron of mass \(m_e\) and a proton of mass \(m_p\) are accelerated through the same potential. Then the ratio of their de Broglie wavelengths is

Light of wavelength 5000 \r{A is incident normally on a slit of width $2.5 \times 10^{-4}$ cm. The angular position of second minimum from the central maximum is}

In Young's double slit experiment, to increase the fringe width

Identify the mismatch in the following

The polarising angle for a medium is found to be \( 60^\circ \). The critical angle of the medium is

The apparent flattening of the sun at sunset and sunrise is due to

Which one of the following is the property of a monochromatic, plane electromagnetic wave in free space?

In a plane electromagnetic wave, the electric field of amplitude \( 1 \text{ V m}^{-1} \) varies with time in free space. The average energy density of magnetic field is (in \( \text{Jm}^{-3} \))

A step down transformer increases the input current 4 A to 24 A at the secondary. If the number of turns in the primary coil is 330, the number of turns in the secondary coil is

A conducting ring of radius 1 m kept in a uniform magnetic field B of 0.01 T, rotates uniformly with an angular velocity 100 rad s\(^{-1}\) with its axis of rotation perpendicular to B. The maximum induced emf in it is

In an LCR series circuit, at resonance

The polarity of induced emf is given by

If a magnetic dipole of moment M situated in the direction of a magnetic field B is rotated by \(180^\circ\), then the amount of work done is

If the radius of the dees of cyclotron is \(r\), then the kinetic energy of a proton of mass \(m\) accelerated by the cyclotron at an oscillating frequency \(\nu\) is

Identify the correctly matched pair

A bar magnet of moment of inertia \(9 \times 10^{-5} \text{ kg m}^2\) placed in a vibration magnetometer and oscillating in a uniform magnetic field \(16\pi^2 \times 10^{-5} \text{ T}\) makes 20 oscillations in 15 s. The magnetic moment of the bar magnet is

The magnitude of the magnetic field inside a long solenoid is increased by

A rigid container with thermally insulated walls contains a gas and a coil of resistance 50 \(\Omega\), carrying a current of 1 A. The change in internal energy of the gas after 2 minutes will be

The power dissipated in the transmission cables carrying current I and voltage V is inversely proportional to

Five cells each of emf E and internal resistance \(r\) send the same amount of current through an external resistance R whether the cells are connected in parallel or in series. Then the ratio \( \left( \frac{R}{r} \right) \) is

If the ammeter A shows a zero reading in the circuit shown below, the value of resistance R is

In the network shown below, if potential across XY is 4 V, then the input potential across AB is

A point charge of 2 C experiences a constant force of 1000 N when moved between two points separated by a distance of 2 cm in a uniform electric field. The potential difference between the two points is

The time period of revolution of a charge \(q_1\) and of mass \(m\) moving in a circular path of radius \(r\) due to Coulomb force of attraction with another charge \(q_2\) at its centre is