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C and Si both have the same lattice structure, having 4 bonding electrons in each. However, C is an insulator whereas Si is an intrinsic semiconductor. This is because:
A transistor is operated in common-emitter configuration at $V_c = 2\text{ V}$ such that a change in the base current from $100\, \mu\text{A}$ to $200\, \mu\text{A}$ produces a change in the collector current from $5\text{ mA}$ to $10\text{ mA}$. The current gain is:
The motion of planets in the solar system is an example of the conservation of:
The venturi-meter works on
An oil drop of 12 excess electrons is held stationary under a constant electric field of $2.55 \times 10^4$ N/C. The density of the oil is $1.26 \text{ g/cm}^3$. The radius of the drop is:
In the circuit shown in the figure, the input voltage $V_i$ is 20 V, $V_{BE} = 0$, and $V_{CE} = 0$. The values of $I_B$, $I_C$ and $\beta$ are given by:
If the lattice parameter for a crystalline structure is $3.6\text{ \AA}$, then the atomic radius in fcc crystal is:
For which one of the following, Bohr model is not valid ?
Which one of the following represents the forward bias diode?
In a double slit experiment, when light of wavelength 400 nm was used, the angular width of the first minima formed on a screen placed 1 m away, was found to be 0.2°. What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? ($\mu_{water} = 4/3$)
Body A of mass 4m moving with speed u collides with another body B of mass 2m, at rest. The collision is head on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is :
An AC voltage is applied to a resistance R and an inductor L in series. If R and the inductive reactance are both equal to 3 Ω, then the phase difference between the applied voltage and the current in the circuit will be:
The solids which have the negative temperature coefficient of resistance are:
Two bodies of mass $1 \text{ kg}$ and $3 \text{ kg}$ have position vectors $\hat{i}+2\hat{j}+\hat{k}$ and $-3\hat{i}-2\hat{j}+\hat{k}$, respectively. The centre of mass of this system has a position vector:
A small-signal voltage $V(t) = V_0 \sin(\omega t)$ is applied across an ideal capacitor C:
A body is rolling without slipping on a horizontal surface and its rotational kinetic energy is equal to the translational kinetic energy. The body is:
Two periodic waves of intensities $I_1$ and $I_2$ pass through a region at the same time in the same direction. The sum of the maximum and minimum intensities is:
A coil of self-inductance L is connected in series with a bulb B and an AC source. The brightness of the bulb decreases when:
If the radius of the earth is suddenly contracted to half of its present value, then the duration of the day will be of:
Four identical thin rods each of mass $M$ and length $t$, form a square frame. Moment of inertia of this frame about an axis through the centre of the square and perpendicular to its plane is: