If the two ends of a p-n junction are joined by a wire:

What would be the effective mass of a photon, if the frequencies of radiation is \(6 \times 10^{14} Hz\) ?

A cell supplies a current of 0.6 A through a 3 \( \Omega \) resistor and a current of 0.2 A through a 10 \( \Omega \) resistor. The internal resistance of the cell is :

Lower half of a convex lens is opaque. The image of an object placed in front will :

At a certain place on earth, the north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points \( 60^{\circ} \) below the horizontal. The horizontal component of the earth's magnetic field is measured to be 0.16 G. The magnitude of the earth's magnetic field at the location is:

Which of the following statements is correct about the effect of the presence of a third charge on Coulomb force between the two charges?

Which of the statements are true, If a convex lens is placed in water:
a. Its focal length increases.
b. Its focal length decreases.
c. Rays bend less when they move through lens.
d. There is no change in radius of curvature.
Choose the correct answer from the options given below :

Which of the following diseases is caused by a virus?

Read the passage and answer the question given below.
When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is called active immunity. Active immunity is slow and takes time to give its full effective response. Injecting the microbes deliberately during immunisation or infectious organisms gaining access into body during natural infection induce active immunity. When antibodies are directly given to protect the body against foreign agents, it is called passive immunity.
Immunity provided to the foetus from the mother through placenta during pregnancy is :

For a long wire carrying a current of \( 10 \text{ A} \), the magnitude of magnetic field at a point \( 4 \text{ cm} \) away from it will be :

If \(f(x)=e^x g(x), g(0)=2, g^{\prime}(0)=1\) then \(f^{\prime}(0)\) is equal to:

A capacitor of unknown capacitance is connected with a battery of V volts. The charge stored in it is \( 200 \, \mu\text{C} \). When the potential of the capacitor is reduced by 100 volts, the charge stored in it becomes \( 150 \, \mu\text{C} \). The unknown capacitance is:

The value of \(\int_{-\frac{\pi}{2}}^{\frac{\pi}{2}}(\sin |x|+\cos |x|) d x\), is equal to: