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

Assertion: A transfonner cannot work on D.C. supply.

Reason: D.C. changes neither in magnitude nor in direction.

The half-life of a radioactive sample undergoing `alpha` - decay is 1.4 x 10¹⁷ s. If the number of nuclei in the sample is 2.0 x 10²¹, the activity of the sample is nearly ____________.

A transformer having efficiency of 80% is working on 200 V and 6 kW power supply. If the current in the secondary coil is 6 A, the voltage across the secondary coil and the current in the primary coil respectively are ____________.

A body of mass 'M' moving with velocity 'V' explodes into two equal parts. If one part comes to rest and the other part moves with velocity 'v₀'. What would be the value of 'v₀'?

The motion of a rocket in upward direction with high speed is based on the principle of conservation of ______.

After 1 hour, `(1/8)^"th"` of the initial mass of a certain radioactive isotope remains undecayed. The half-life of the isotopes is ______.

A 100% efficient transformer has 100 turns in the primary and 50 turns in its secondary coil. If the current in the secondary coil is 6 A, then the current in the primary coil is ______.

Two radioactive materials Y₁ and Y₂ have decay constants '5`lambda`' and `lambda` respectively. Initially they have same number of nuclei. After time 't', the ratio of number of nuclei of Y₁ to that of Y₂ is `1/"e"`, then 't' is equal to ______.

What percentage of radioactive substance is left after five half-lives?

A rectangular block of mass 'm' and cross-sectional area 'A' floats on a liquid of density ρ. If it is given a small vertical displacement from equilibrium, it starts oscillating with frequency 'n' equal to ______.

(g = acceleration due to gravity)

What is the half-life period of a radioactive material if its activity drops to 1/16^th of its initial value of 30 years?

The magnetic flux through a coil perpendicular to its plane is varying according to the relation Φ = (5t³ + 4t² + 2t - 5) Weber. If the resistant of the coil is 5 ohm, then the induced current through the coil at t = 2 sec will be ______.

Magnetic flux Φ in weber in a closed circuit of resistance 10Ω varies with time Φ (sec) as Φ = 6t² - 5t + 1. The magnitude of induced current at t = 0.25s is ______.

AU-tube is of non uniform cross-section. The area of cross-sections of two sides of tube are A and 2A (see fig.). It contains non-viscous liquid of mass m. The liquid is displaced slightly and free to oscillate. Its time period of oscillations is ______.

An ideal transformer converts 220 V a.c. to 3.3 kV a.c. to transmit a power of 4.4 kW. If primary coil has 600 turns, then alternating current in secondary coil is ______.

Two coils P and Q are kept near each other. When no current flows through coil P and current increase in coil Q at the rate 10A/s, the emf in coil P is 15mV. When coil Q carries no current and current of 1. 8A flows through coil P, the magnetic flux linked with the coil Q is ______.

An iron rod is placed parallel to magnetic field of intensity 2000 Am^-1. The magnetic flux through the rod is 6 × 10⁻⁴ Wb and its cross-sectional area is 3 cm². The magnetic permeability of the rod in Wb A^-1m^-1 is ______.

Magnetic flux passing through a coil is initially 4 × 10^-4 Wb. It reduces to 10% of its original value in t second. If the emf induced is 0. 72 mV then t in second is ______.

An iron rod of 0.2 cm² cross-sectional area is subjected to a magnetising field of 1200 Am^-1. If the susceptibility of iron is 599, then the magnetic flux produced is ______.

A thin uniform rod has mass M and length L The moment of inertia about an axis perpendicular to it and passing through the point at a distance `"L"/3` from one of its ends, will be ______.