List of top Physics Questions asked in OJEE

A battery of 10 V and internal resistance 0.5 Ω is connected in parallel with a battery of 12 V and internal resistance 0.8 Ω. The terminals are connected by an external resistance of 20 Ω. The current flowing through the 20 Ω resistance is:
A coil has resistance 20 Ω and inductance 0.35 H. Compute its impedance to an alternating current of 25 cycles/s.
How far should an object be from a concave spherical mirror of radius 36 cm to form a real image one-ninth its size?
A wire 0.5 m long and with a mass per unit length of 0.0001 kg/m vibrates under a tension of 4 N. The fundamental frequency is:
A wave along a string has the following equation \( y = 0.02 \sin [30t – 4.0x] \) m. The speed of the wave is:
A drop of water of radius 0.01 m is falling through a medium whose density is 1.21 kg/m\(^3\) and co-efficient of viscosity \( \eta = 1.8 \times 10^{-5} \, \text{Ns/m}^2 \). Then the terminal velocity of the drop is:
At temperature 'T', the 'effective' speed of gaseous hydrogen molecules (molecular weight = 2) is equal to that of oxygen molecules (molecular weight = 32) at 47°C. The value of 'T' is:
A glass bulb of volume 400 cm\(^3\) is connected to another bulb of volume 200 cm\(^3\) by means of a tube of negligible volume. The bulbs contain dry air. They are both at a common temperature and pressure of 20°C and 1.000 atm. The larger bulb is immersed in steam at 100°C; the smaller, in melting ice at 0°C. The final common pressure is:
A sphere of 3 cm radius acts like a black body. It is in equilibrium with its surrounding and absorbs 30 kW of power radiated to it from surroundings. The temperature of the sphere is \( \sigma = 5.67 \times 10^{-8} \, \text{W/m}^2\text{K}^4 \). What is the temperature of the sphere?
The amount of moisture that must evaporate from a 5.0 kg body to reduce its temperature by 2°C is \( m \) g. The heat of vaporization for water at body temperature is about 580 cal/g. The specific heat capacity for the body is 0.83 cal/g°C. The value of \( m \) is:
100 Vernier scale divisions match with 99 main scale divisions of a slide caliper. If the value of each main scale division is 1 mm, then the Vernier constant is:
One mole of helium gas, initially at STP (p₁ = 1 atm, T₁ = 0°C), undergoes an isovolumetric process in which its pressure falls to half its initial value. The work done by the gas is:
A charge \( q \) is placed at the centre of the line joining two equal charges \( Q \). The system of the three charges will be in equilibrium if \( q \) is equal to:
In a diesel engine, the cylinder compresses air from approximately standard pressure and temperature to about one-sixteenth the original volume and a pressure of about 50 atm. The temperature of the compressed air is:
From the measurement made on the Earth, it is known that the Sun has a surface area of \( 6.1 \times 10^{18} \) m\(^2\) and radiates energy at the rate of \( 3.9 \times 10^{26} \) W. Assuming that the emissivity of the Sun's surface is 1, the temperature of the Sun's surface is:
Same quantity of ice is filled in each of the two identical metal containers P and Q having the same size and shape but of different materials. In P ice melts completely in time \( t_1 \), whereas in Q the time taken is \( t_2 \). Then the ratio of conductivities of P and Q is:
The temperatures of two bodies differ by 1°C. How much will they differ on Fahrenheit scale?
A hole of area 1 mm\(^2\) opens in the pipe near the lower end of a large water storage tank, and a stream of water shoots from it. If the top of the water in the tank is 20 m above the point of the leak, the amount of water escapes in 1 s is:
The volume of an air bubble is doubled as it rises from the bottom of a lake to its surface. The atmospheric pressure is 75 cm of mercury and the ratio of the density of mercury to that of lake water is 40/3. The depth of the lake is:
Water is flowing through a tube of radius \( r \) with a speed \( v \). If this tube is joined to another tube of radius \( r/2 \), the speed of water in the second tube is:
The increase in pressure required to decrease the volume of 200 L of water by 0.004 percent is (Bulk modulus of water is \( 2.1 \times 10^9 \) N/m\(^2\)):
The velocity of a particular mass \( m \) is \( \vec{v} = 5 \hat{i} + 4 \hat{j} + 6 \hat{k} \) when at \( \vec{r} = -2 \hat{i} + 4 \hat{j} + 6 \hat{k} \). The angular momentum of the particle about the origin is:
The two wires A and B of the same material have their lengths in the ratio 1 : 2 and their diameters in the ratio 2 : 1. If they are stretched with the same force, the ratio of the increase in the length of A to that of B will be:
A uniform hollow cylinder has a density \( \rho \), a length \( L \), an inner radius \( a \), and an outer radius \( b \). Its moment of inertia about the axis of the cylinder is (Mass of the cylinder is \( M \)):
A disk of 10 cm radius has a moment of inertia of 0.02 kg.m\(^2\). A force of 15 N is applied tangentially to the periphery of the disk to give it an angular acceleration \( \alpha \) of magnitude: