JEE Main Test 1...

Two identical charged spheres suspended from a common point by two massless strings of length l are initially a distance d(d < < l) apart because of their mutual repulsion. The charge begins to leak from both the spheres at a constant rate. As a result charges approach each other with a velocity v. Then, as a function of distance x between them

How many times more intense is a 60 dB sound than a dB sound?

sech^-1 (sin θ) is equal to

A battery of emf E has an internal resistance r. A variable resistance R is connected to the terminals of the battery. A current i is drawn from the battery. V is the terminal potential difference. If R alone is gradually reduced to zero, which of the following best describes i and V?

A parallel plate air capacitor has a capacitance C. When it is half filled with a dielectric of dielectric constant 5, the percentage increase in the capacitance will be

If the lines x + 3y - 9 = 0, 4x + by - 2 = 0 and 2x - y - 4 = 0 are concurrent, then b is equal to

The number of turns in primary and secondary coils of a transformer is 50 and 200, respectively. If the current in the primary coil is 4 A, then the current in the secondary coil is

Which types of losses do not occur in the transformer ?

A circular coil of radius R = 10 cm having 500 turns and total resistance 2 Ω is placed initially perpendicular to the earth's magnetic field of 3 × 10^-5 T. The coil is rotated about its vertical diameter by an angle 2π in 0.5 . The induced current in the coil is