Physics Test 222

A pipe of length 85 cm is closed from one end. Find the number of possible natural oscillations of air column in the pipe whose frequencies lie below 1250 Hz. The velocity of sound in air is 340 m/s.

The current voltage relation of diode is given by  where the applied voltage V is in volts and the temperature T is in degree Kelvin. If a student makes an error measuring ±0.01 V while measuring the current of 5 mA at 300 K, what will be the error in the value of current in mA?

The forward biased diode connection is

An LCR circuit is equivalent to a damped pendulum. In an LCR circuit, the capacitor is charged to Q₀ and then connected to the L and R as shown below:

If a student plots graphs of the square of maximum charge  on the capacitor with time (t) for two different values L₁ and L₂ (L₁ > L₂) of L, then which of the following represents this graph correctly?

(Plots are schematic and not drawn to scale)

In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1kW. The voltage of the electric mains is 220 V. The minimum capacity of the main fuse of the building will be

From a tower of height H, a particle is thrown vertically upwards with a speed u. The time taken by the particle, to hit the ground, is n times that taken by it to reach the highest point of its path. The relation between H, u and n is

Two masses m and m/2 are connected at the two ends of a massless rigid rod of length l. The rod is suspended by a thin wire of torsional constant k at the centre of mass of the rod-mass system (see figure). Because of torsional constant k, the restoring torque is τ = kθ for angular displacement θ. If the rod is rotated by θ₀ and released, the tension in it when it passes through its mean position will be:

From a solid sphere of mass M and radius R, a cube of maximum possible volume is cut. Moment of inertia of cube about an axis passing through its centre and perpendicular to one of its faces, is

On a hot summer night, the refractive index of air is the smallest near the ground and increases with height from the ground. When a light beam is directed horizontally, the Huygens' principle leads us to conclude that as it travels, the light beam

A triode has a plate resistance of 10 kΩ and amplification factor 24. If the input signal voltage is 0.4 V (r.m.s.), and the load resistance is 10 k ohm, then, the output voltage (r.m.s.) is