List of top Physics Questions

A convex lens of glass is immersed in water compared to its power in air, its power in water will
A uniform disc of mass $M$ and radius $R$ is mounted on an axle supported in friction less bearings. A light cord is wrapped around the rim of the disc and a steady downward pull $T$ is exerted on the cord. The angular acceleration of the disc is:
A $6\, V$ battery is connected to the terminals of a three metre long wire of uniform thickness and resistance of $ 100\,\Omega $ . The difference of potential between two points on the wire separated by a distance of $50 \,cm$ will be
A person covers the first half of the distance with 6 m/s and the rest half with 9 m/s and 15 m/s in two equal time intervals. Find the average speed of the journey.
A ballet dancer, dancing on a smooth floor is spinning about a vertical axis with her arms folded with an angular velocity of $20 \,rad/s$. When she stretches her arms fully, the spinning speed decrease as $10\, rad/s$. If $I$ is the initial moment of inertia of the dancer, the new moment of inertia is
Near a circular loop of conducting wire as shown in the figure an electron moves along a straight line. The direction of the induced current if any in the loop is
The heat of combustion of a substance is :

Three capacitors each of capacitance 9 pF are connected in series. 

(a) What is the total capacitance of the combination? 

(b) What is the potential difference across each capacitor if the combination is connected to a 120 V supply?

A train of length $L$ move with a constant speed $V_t$. A person at the back of the train fires a bullet at time $t = 0$ towards a target which is at a distance of $D$ (at time $t =0$) from the front of the train (on the same direction of motion). Another person at the front of the train fires another bullet at time $t\, = \,T$ towards the same target. Both bullets reach the target at the same time. Assuming the speed of the bullets, $V_b$, are same, the length of the train is
Given a + b + c + d = 0, which of the following statements are correct:
a) a, b, c, and d must each be a null vector.
b) The magnitude of (a + c) equals the magnitude of (b+ d). 
c) The magnitude of a can never be greater than the sum of the magnitudes of b, c, and d. 
d) b + c must lie in the plane of a and d if a and d are not collinear, and in the line of a and d, if they are collinear?
A uniform circular metal disc of radius $R$ is rotating about a vertical axis passing through its center and perpendicular to its plane with constant frequency f. If $B_H$ and $B_v$ are horizontal and verticaI components of the Earth's magnetic field respectively, then the induced e.m.f between its center and the rim is
Kirchhoff's first rule of any junction of several circuit element in an electric circuit is based on the law of conservation of:

A series LCR circuit connected to a variable frequency 230 V source. L = 5.0 H, C = 80mF, R = 40 Ω.

(a) Determine the source frequency which drives the circuit in resonance.

(b) Obtain the impedance of the circuit and the amplitude of current at the resonating frequency.

(c) Determine the rms potential drops across the three elements of the circuit. Show that the potential drop across the LC combination is zero at the resonating frequency

Steam at 100∘C is passed into 1.1 kg of water contained in calorimeter of water equivalent 0.02 kg at 15∘C till the temperature of the calorimeter rises to 800C. What is the mass of steam condensed?
A block of mass m = 5 kg is on the smooth inclined face of the wedge of mass M  = 10 kg , the inclination to the horizontal being θ = 37°.The wedge is resting on a smooth horizontal plane. Assuming the pulley P to be smooth and the string is light and inextensible. Find the acceleration of M, when M and m are always in contact.
[Given that Sin 37o=35 ]
Two thin convex lenses of focal lengths f1 and f2 are separated by a horizontal distance d (where d < f1, d < f2) and their centers are displaced by a vertical separation Δ as shown in the figure.
Taking the origin of coordinates, O at the center of the first lens, the x and y-coordinates of the focal point of this lens system, for a parallel beam of rays coming from the left, are given by
A thin concave lens is in contact with a thin convex lens. The ratio of their magnitude of the focal length is 32 and the focal length of the combined lens is 30 cm. The focal lengths of the individual lenses are
A compressive force, F is applied at the two ends of a long thin steel rod. It is heated, simultaneously, such that its temperature increases by ΔT. The net change in its length is zero. Let L be the length of the rod, A is its area of cross-section. Y is Young’s modulus, and α is its coefficient of linear expansion. Then, F is equal to
If the resultant of the vectors shown in A√x, find x.
the resultant of the vectors
If subtraction of two vectors is also a unit vector then the angle between the first two vectors is
The characteristics of photoelectric effect which supports the particle nature of radiation is
A system consisting of two masses connected by a massless rod lies along the x-axis. A 0.4 kg mass is at a distance x = 2 m while a 0.6 kg mass is at a distance x = 7 m. The x-coordinate of the center of mass is
When the temperature exceeds the transition temperature, a ferromagnetic material becomes similar to:
A 5V battery with internal resistance 2Ω and a 2V battery with internal resistance 1Ω are connected to a 10Ω resistor as shown in the figure. The current in the 10Ω resistor is
Three identical thin rods each of length l and mass M are joined together to form a letter H. What is the moment of inertia of the system about one of the sides of H ?