Browse and search thousands of solved questions for your preparation.
Free questions with full explanations — locked behind signup to protect quality.
A very long conducting wire is bent in a semi-circular shape from A to B as shown in the figure. The magnetic field at the point P for steady current configuration is given by:
In forward biasing of the p-n junction:
Identify the equivalent logic gate represented by the circuit given below:
Which of the following statements is true for nuclear forces?
Two nuclei have their mass numbers in the ratio of 1:3. The ratio of their nuclear densities would be:
The rate of radioactive disintegration at an instant for a radioactive sample of half-life $2.2 \times 10^9 \text{ s}$ is $10^{10} \text{ s}^{-1}$. The number of radioactive atoms in that sample at that instant is:
What happens to the mass number and the atomic number of an element when it emits $\gamma$-radiation?
If a nucleus $_n X^m$ emits one $\alpha$ and two $\beta$ particles, the resulting nucleus will be:
A human body required the $0.01\text{ Curie}$ activity of a radioactive substance after $24\text{ hours}$. The half-life of the radioactive substance is $6\text{ hours}$. The maximum activity of the radioactive substance that can be injected will be:
The power obtained in a reactor using U-235 disintegration is 1000 kW. The mass decay of U-235 per hour is:
The numbers of nuclei of a radioactive substance at time t = 0 are 1000 and 900 at time t = 2 sec. Then the number of nuclei at time t = 4 sec will be:
Out of the following which one is a forward-biased diode?
10 g of radioactive material of half-life 15 year is kept in store for 20 years. The disintegrated material mass is
Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t = 0, the number of P species are 4N_0 and that of Q is N_0. Half-life of P (for conversion to R) is 1 min whereas that of Q is 2 min. Initially there are no nuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be:
A mass of $2.0\text{ kg}$ is put on a flat pan attached to a vertical spring fixed on the ground as shown in the figure. The mass of the spring and the pan is negligible. When pressed slightly and released, the mass executes a simple harmonic motion. The spring constant is $200\text{ N/m}$. What should be the minimum amplitude of the motion, so that the mass gets detached from the pan? (Take $g=10\text{ m/s}^2$)
A boy is trying to start a fire by focusing sunlight on a piece of paper using an equiconvex lens of a focal length of $10 \text{ cm}$. The diameter of the sun is $1.39 \times 10^9 \text{ m}$ and its mean distance from the earth is $1.5 \times 10^{11} \text{ m}$. What is the diameter of the sun's image on the paper?
The intensity at the maximum in Young's double-slit experiment is $I_0$ when the distance between two slits is $d=5\lambda$, where $\lambda$ is the wavelength of light used in the experiment. What will be the intensity in front of one of the slits on the screen placed at a distance $D= 10d$?
The half-life of a radioactive nuclide is 100 hours. The fraction of original activity that will remain after 150 hours would be:
The SI unit of universal gas constant (R) is
The half-life of a radioactive substance is 20 minutes. In how much time, the activity of substance drops to $(1/16)^{th}$ of its initial value?