JEE Main entrance exam Question Bank Solutions for Physics (JEE Main)

If 10% of a radioactive substance decays in every 5 years, then the percentage of the substance that will have decayed in 20 years will be ______.

A light ray in a medium (RI = 5/3) enters another medium at an angle of 30°. The angle in the other medium is sin^-1 (5/6). The incident angle must be increased such that the ray is completely reflected at minimum degrees is ______.

Two radioactive materials A and B have decay constants 25λ and 16λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of B to that of A will be "e" after a time `1/("a"lambda)` The value of a ______.

A radioctive sample decays `7/8` times its original quantity in 15 minutes. The half-life of the sample is ______.

Calculate the time interval between 33% decay and 67% decay if half-life of a substance is 20 minutes.

If L, C and R are the self inductance, capacitance and resistance respectively, which of the following does not have the dimension of time?

Which of the following is not a dimensionless quantity?

Which one of the following represents the correct dimensions of the coefficient of viscosity? 

The missing number is ______ in the expression given below A = `se^{(at^x)/A}` where s : displacement, t : time, a : acceleration.

A monkey of mass 50 kg climbs on a rope which can withstand the tension (T) of 350 N. If monkey initially climbs down with an acceleration of 4 m/s² and then climbs up with an acceleration of 5m/s². Choose the corret option (g = 10 m/s²)

A mass of 10 kg is suspended vertically by a rope of length 5m from the roof. A force of 30 N is applied at the middle point of rope in horizontal direction. The angle made by upper half of the rope with vertical is θ = tan^-1(x × 10^-1). The value of x is ______.

(Given g = 10 m/s²)

A person standing on a spring balance inside a stationary lift measures 60 kg. The weight of that person if the lift descends with uniform downward acceleration of 1.8 m/s² will be ______ N. [g = 10 m/s²]

Two satellites A and B having masses in the ratio 4 : 3 are revolving in circular orbits of radii 3r and 4r respectively around the Earth. The ratio of total mechanical energy of A to B is ______.

The displacement y of a particle in a medium can be expressed as, y = `10^-6sin(100t + 20x + pi/4)` m where t is in second and x in meter. The speed of the wave is ______.

A block of mass m slides along a floor while a force of magnitude F is applied to it at an angle θ as shown in figure. The coefficient of kinetic friction is µK. Then, the block's acceleration 'a' is given by ______.

(g is acceleration due to gravity)

A uniform chain of length 3 metres and mass 3 kg overhangs a smooth table with 2 metres laying on the table. If k is the kinetic energy of the chain in joule as it completely slips off the table, then the value of k is ______.

(Take g = 10 m/s²)

If T be the total time of flight of a current of water and H be the maximum height attained by it from the point of projection, then HIT will be : (u = projection velocity, e = projection angle)

Two particles are projected simultaneously from the level ground as shown in figure. They may collide after a time:

If a body of mass m is moving on a rough horizontal surface of coefficient of kinetic friction µ, the net resultant force exerted by surface on the body is ______.

If a baseball player can throw a ball at maximum distance = d over a ground, the maximum vertical height to which he can throw it, will be (Ball has same initial speed in each case):