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. December 2016

Electrostatics: Capacitor

Q- A parallel plate capacitor is having capacitance 50 nF and given a charge of 2µC.

(a) If an electron escapes from the negative plate, how much kinetic energy it will gain while reaching positive plate?

(b) How much energy is stored in the electric field between the plates?

(c) If the plates…

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Variable Force

Q- Consider an object on which the net force is a resistive force proportional to the square of its velocity as F = -kmv2, where k is a constant and m is mass of the object. At t = 0 the speed of the object is Vo. Find an expression for the speed of the object at subsequent time t.

Solution:

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Photo Electric Effect

Q- Light from a laser hits the surface of cesium, with minimum photon energy of 2.5 eV being required to remove photons. When the surface of cesium is illuminated with this light photo-electrons are emitted with a max kinetic energy of 0.75 eV. What would be the energy of the photons comprising the …

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Gravitation

Q- A straight tunnel is dug through the earth (not passing through the center). Show that neglecting any resistive force the motion of an object inside the tunnel is simple harmonic motion and find the expression for time period of the motion.

Solution:

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Wave Optics: Polarization

Q- A polarizer is followed by n analyzers, each tilted by 0.54 degree with respect to the previous. How many analyzers are required to reduce the intensity by a factor of 1/50 that which is entering the polarizer?

Solution:

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Thermal Physics: Boyle's Law

Q- A scuba diver releases a 2.50 cm diameter (spherical) bubble of air from a depth of 15 m in a lake. Assume the temperature is constant at 16.0C, and the air behaves as a perfect gas. What is the diameter of the bubble when it reaches the surface?

Solution:

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Radiation

Q- Find the mean radiation power of an electron performing harmonic oscillations with amplitude a = 0.10 nm and frequency f = 6.5 X 1014 s-1

Solution:

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Conservation of Momentum

Q- A 65.0 kg boy and his 40.0 kg sister, both wearing roller blades, face each other at rest. The girl pushes the boy hard, sending him backward with a velocity 2.90 m/s toward the west. Ignore friction.

(a) Describe the subsequent motion of the girl.

(b) How much chemical energy is converted in…

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Ray Optics: Refraction

Q- An object is placed 25 cm in air from a concave refracting surface. The surface has a radius of curvature of 5 cm, and the refractive index is 1.70. Determine the refracted image position and orientation.

Solution;

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Simple Harmonic Motion

Q- A small block of mass 80 g is oscillating on a spring. The equation of motion for its position x as a function of time is given by

                   x(t) = (5.0 cm) cos (10t + π/4)

(a) what is the amplitude of the oscillation?

(b) What is the period of oscillation?

(c) What is the…

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Capacitor

Q- Find the equivalent capacitance between points a and b in the combination of capacitors shown in Figure. C1 = 2.0 µF and C2 = 3.0 µF.

Solution:

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Rotational motion

Q- A billiard ball of mass m rolls without slipping across a table at speed v0. It collides with the lower end of a rod of mass M = 2m and length d, pivoted at its center and initially at rest in vertical position. After collision the ball rolls straight with half of its initial speed. What is the r…

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Fluids

Q- A siphon tube is filled with gasoline and closed at each end. One end is inserted into a gasoline tank 0.20 m below the surface of the gasoline. The outlet is placed outside the tank at a distance 0.50 m below the surface of the gasoline. The tube has an inner cross-sectional area of 4.2*10-4 m2.…

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AC: Inductance

Q- A pure inductance L is connected to an AC circuit and the maximum voltage across it is Vmax = 100V.

(a) If the maximum current is 7.5A at 50Hz, calculate the inductance L

(b) At what angular frequency (ω) is the maximum current 2.5A?

Solution:

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Gravitation: Escape Velocity

Q- A particle is projected from the surface of the earth with speed twice the escape speed. When it is very far from the earth, what is its speed?

Solution:

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Motion in 2 D: Relative velocity

Q- A boat is trying to get from point A to point B, which is exactly to the east of A. The ocean current is due north at 4.8 km/h. The boat speed relative to the water is 18 km/h.

a) If the captain heads his boat due east, what will be his actual course relative to the shore? 

b) To attain a stra…

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Electrostatics: Field due to a charged cylinder

Q- A hollow cylinder of radius a and length L, open at its ends, carries a uniform surface charge density σ. Use the formula for electric field due to a thin uniformly charged ring; find the expression for the electric field at a point P on the axis of the cylinder at a distance b from its nearest …

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