Class 12th

In the reported figure, a capacitor is formed by placing a compound dielectric between the plates of parallel plate capacitor. The expression for the capacity of the said capacitor will be: (Given area of plate = A)

The half-life of ¹?Au is 3 days. If atomic weight of ¹?Au is 198 g/mol then the activity of 2 mg of ¹?Au is [ in disintegration / second ] :

A capacitor of capacitance C = 1µF is suddenly connected to a battery of 100 volt through a resistance R = 100Ω. The time taken for the capacitor to be charged to get 50 V is: [Take ln 2 = 0.69]

A parallel plate capacitor with plate area 'A' and distance of separation 'd' is filled with a dielectric. What is the capacity of the capacitor when permittivity of the dielectric varies as

ε(x) = ε? + kx, for 0 < x d/2
ε(x) = ε? + k(d-x), for d/2 ≤ x ≤ d

In the given figure, a battery of emf E is connected across a conductor PQ of length 'l' and different area of cross- sections by having radii r? and r? (r? < r?). Choose the correct option as one moves from P to Q:

In Amplitude Modulation, the message signal V?(t) = 10 sin(2π * 10?t) volts and carrier signal V?(t) = 20 sin(2π * 10?t) volts. The modulated signal now contains the message signal with lower side band and upper side band frequency, therefore the bandwidth of modulated signal is α kHz. The value of α is:

Two identical tennis balls each having mass 'm' and charge 'q' are suspended from a fixed point by threads of length 'l'. What is the equilibrium separation when each thread makes a small angle 'θ' with the vertical?

A 16Ω wire is bend to form a square loop. A 9V supply having internal resistance of 1Ω is connected across one of its sides. The potential drop across the diagonals of the square loop is __________ x 10?¹ V.

From the given data, the amount of energy required to break the nucleus of aluminium ²⁷₁₃Al is x * 10⁻³ J.
Mass of neutron = 1.00866 u
Mass of proton = 1.00726 u
Mass of Aluminium nucleus = 27.18846 u
(Assume 1 u corresponds to x J of energy)
(Round off to the nearest integer)

The given potentiometer has its wire of resistance 10Ω. When the sliding contact is in the middle of the potentiometer wire, the potential drop across 2Ω resistor is :