List of top Physics Questions

A transistor is operated in common emitter configuration at constant collector voltage VC = 1.5 V such that a change in the base current from 100 µA to 150 µA produces a change in the collector current from 5 mA to 10 mA. The current gain (β) is :
In a discharge tube ionization of enclosed gas is produced due to collisions between :
A forward biased diode is :
Ionization potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.1 eV. According to Bohr's theory, the spectral lines emitted by hydrogen will be :
In a radioactive material the activity at time t1 is R1 and at a later time t2, it is R2. If the decay constant of the material is \(\lambda\), then :
A transistor-oscillator using a resonant circuit with an inductor L (of negligible resistance) and a capacitor C in series produce oscillations of frequency f. If L is doubled and C is changed to 4C, the frequency will be :
Refractive index of ionosphere is
Circular loop of a wire and a long straight wire carry currents $I _{ c }$ and $I _{ e }$, respectively as shown in figure. Assuming that these are placed in the same plane. The magnetic field will be zero at the centre of the loop when the separation $H$ is :
When a spring is stretched by a distance $x$, it exerts a force, given by $F = (-5x - 16x^{3})\, N$. The work done, when the spring is stretched from $0.1 \,m$ to $0.2\, m $ is
The $(x, y, z)$ coordinates of two points $A$ and $B$ are given respectively as $(0, 3,-1)$ and $(-2, 6, 4)$. The displacement vector form $A$ to $B$ may be given by:
A wire of resistance 5 ohms is stretched such that longitudinal strain is $200 \%$.The new resistance in ohms is
A slit of width 0.1 mm is illuminated normally d by light of $\lambda = 5000 \mathring A $. Diffraction bands are observed on a screen, 1 m away from the slit. Third dark band is at a distance x from the central maximum. x is approximately
Two bars of radius r and 2rare kept in contact as shown. An electric current I is passed through the bars. Which one of following is correct ?
A galvanometer has a resistance $ 50\,\Omega $ . A resistance of $ 5\,\Omega $ is connected parallel to it. Fraction of the total current flowing through galvanometer is
What is the potential drop between points $A$ and $C$ in the following circuit? Resistances $ 1 \omega $ and $ 2 \omega $ are represent the internal resistance of the respective cells.
At the instant, when potentiometer is balanced, current
To decrease the range of an ammeter, its resistance need to be increased. An ammeter has resistance $ R_0 $ and range I. Which of the following resistance can be connected in series with it to decrease its range to $ \frac{1}{n} $ ?
A thermocouple is made from two metals, Antimony and Bismuth. If one junction of the couple is kept hot and the other is kept cold, then, an electric current will:
The current $I$ drawn from the $5$ volt source will be:
The resistance of a bulb filament is $100\, \Omega$ at a temperature of $100^?C$. If its temperature coefficient of resistance be $0.005$ per $^?C$, its resistance will become $200\,\Omega$ at a temperature of:
An electric bulb is rated 220 volt - 100 watt. The power consumed by it when operated on 110 volt will be :
Function $ x = A sin ^2 \omega t + B cos^ 2 \omega t + C sin \omega t cos \omega t $ represents SHM
The length of second's pendulum is 1 m on earth. If mass and diameter of a planet is doubled than that of earth, then its length becomes
What effect occurs on the frequency of a pendulum if it is taken from the earth's surface to deep into a mine?
A coin is placed on a horizontal platform which undergoes vertical simple harmonic motion of angular frequency $\omega$ . The amplitude of oscillation is gradually increased. The coin will leave contact with the platform for the first time: