1. The age of a rock containing lead and uranium is equal to 1.5 × 109 yrs. The uranium is decaying into lead with half life equal to 4.5 × 109 yrs. Find the ratio of lead to uranium present in the rock, assuming initially no lead was present in the rock. (Given 21/3 = 1.259)
2. An inductor of inductance (L) equal to 35 mH
and resistance (R) equal to 11 Ω are connected
in series to an AC source. The rms voltage of
a.c. source is 220 volts and frequency is 50 Hz.
Find the peak value of current in the circuit.
Two identical blocks A and B are placed on a rough inclined plane of
inclination 45°. The coefficient of friction between block A and incline is
0.2 and that of between B and incline is 0.3. The initial separation between
the two blocks is √2 m. The two blocks are released from rest, then find
3. the time after which front faces of both blocks come in same line
4. the distance moved by each block for attaining above position.
5. In a photoelectric setup, the radiations from the Balmer series of hydrogen atom are incident on a metal
surface of work function 2eV. The wavelength of incident radiations lies between 450 nm to 700 nm. Find
the maximum kinetic energy of photoelectron emitted.
(Given hc/e = 1242 eV-nm).
Source 2004 jee main