MAH-MHT CET (PCM/PCB) entrance exam Question Bank Solutions for Physics

A dielectric is inserted between the plates of a charged and isolated parallel-plate air capacitor. Then, the charge on the plates and the potential difference, respectively, ______.

Capacity of a parallel plate capacitor with a medium of dielectric constant 8 is 12 µF. If the medium is removed, then capacity of the capacitor would be ____________.

The moment of inertia of a sphere is 20 kg-m² about the diameter. The moment of inertia about any tangent is ____________.

A particle of mass 'm' collides with another stationary particle of mass 'M'. A particle of mass 'm' stops just after collision. The coefficient of restitution is ______.

A wooden block of mass 'M' moves with velocity 'v ' and collides with another block of mass '4M' which is at rest. After collision, the block of mass 'M' comes to rest. The coefficient of restitution will be ______.

A block of mass 'm' moving along a straight line with constant velocity `3vec"v"` collides with another block of same mass at rest. They stick together and move with common velocity. The common velocity is ______.

A disc of mass 100 kg and radius 1 m is rotating at 300 rpm. The torque required to rotate the disc in opposite direction with same speed in time 50 second is ______.

A toroid is a long coil of wire wound over a circular core. If 'r' and 'R' are the radii of the coil and toroid respectively, the coefficient of self-induction of the toroid is (The magnetic field in it is uniform and R > > r) ____________.

(N = number of turns of the coil and µ₀ = permeability of free space)

Two discs having moment of inertia I₁ and I₂ are made from same material have same mass. Their thickness and radii are t₁, t_2, and R₁, R₂ respectively. The relation between moment of inertia of each disc about an axis passing through its centre and perpendicular to its plane and its thickness is ______.

The magnetic flux near the axis and inside the air core solenoid of length 60 cm carrying current 'I' is 1.57 × 10^-6 Wb. Its magnetic moment will be ______.

(cross-sectional area is very small as compared to length of solenoid, µ₀ = 4π × 10^-7 SI unit)

Magnetic field at the centre of a circular loop of area 'A' is 'B'. The magnetic moment of the loop will be (µ₀ = permeability of free space) ____________.

A thin uniform rod of length 'L' and mass 'M' is bent at the middle point 'O' at an angle of 45° as shown in the figure. The moment of inertia of the system about an axis passing through 'O' and perpendicular to the plane of the bent rod, is ______.

A fix number of spherical drops of a liquid of radius 'r' coalesce to form a large drop of radius 'R' and volume 'V'. If 'T' is the surface tension then energy ______.

A water film is formed between the two straight parallel wires, each of length 10 cm, kept at a separation of 0.5 cm. Now, the separation between them is increased by 1 mm without breaking the water film. The work done for this is ______.

(surface tension of water = 7.2 x 10^-2Nm^-1)

A capacitor of unknown capacitance is connected across a battery of 'V' volt. The charge stored in it is 'Q' coulomb. When the potential across the capacitor is reduced by 'V' volt, the charge stored in it becomes Q' coulomb. The potential V is ______ 

A parallel plate capacitor has a uniform electric field `overset(->)("E")` in the space between the plates. If the distance between plates is 'd' and the area of each plate is 'A', the energy stored in the capacitor is ______ 

(ε₀ = permittivity of free space)

Four capacitors of equal capacity have an equivalent capacitance C₁ when connected in series and an equivalent capacitance C₂ when connected in parallel. The ratio `c_2/c_1`, is ______

A long solenoid carrying current 'I₁' produces magnetic field 'B₁' along its axis. If the current is reduced to 25% and number of turns per cm are increased four times, then new magnetic field 'B₂' is ____________.

Figure shows triangular lamina which can rotate about different axis of rotation. Moment of inertia is maximum about the axis ______.

Two bodies of masses 3 kg and 2 kg collide bead-on. Their relative velocities before and after collision are 20 m/s and 5 m/s respectively. The loss of kinetic energy of the system is ______.