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A $12\text{ V}$, $60\text{ W}$ lamp is connected to the secondary of a step-down transformer, whose primary is connected to ac mains of $220\text{ V}$. Assuming the transformer to be ideal, what is the current in the primary winding?
The effective acceleration of a body, when thrown upwards with acceleration $a$ (in a frame moving with acceleration $a$) will be:
A police jeep is chasing with a velocity of $45 \text{ km/h}$ a thief in another jeep moving with a velocity of $153 \text{ km/h}$. Police fire a bullet with a muzzle velocity of $180 \text{ m/s}$. The velocity with which it will strike the car of the thief is:
A $120 \text{ m}$ long train is moving in a direction with speed $20 \text{ m/s}$. A train B moving with $30 \text{ m/s}$ in the opposite direction and $130 \text{ m}$ long crosses the first train in a time:
Two balls are dropped from heights h and 2h respectively from the earth surface. The ratio of time of these balls to reach the earth is:
A ball is dropped on the floor from a height of $10 \text{ m}$. It rebounds to a height of $2.5 \text{ m}$. If the ball is in contact with the floor for $0.01 \text{ sec}$, the average acceleration during contact is:
The electric charge in uniform motion produces :
A man throws balls with the same speed vertically upwards one after the other at an interval of 2 seconds. What should be the speed of the throw so that more than two balls are in the sky at any time? (Given $g=9.8 \text{ m/s}^2$)
A body is released from the top of a tower of height $h$. It takes $t$ sec to reach the ground. Where will be the ball after time $t/2$ sec?
A galvanometer has a coil of resistance $100\Omega$ and gives a full scale deflection for $30 \text{ mA}$ current. If it is to work as a voltmeter of $30\text{ V}$ range, the resistance required to be added will be
When a proton is released from rest in a room, it starts with an initial acceleration $a_0$ towards the east. When it is projected towards the north with a speed $v_0$, it moves with initial acceleration $3a_0$ towards east. The electric and magnetic fields in the room are:
A particle having a mass of $10^{-2}$ kg carries a charge of $5 \times 10^{-8}$ C. The particle is given an initial horizontal velocity of $10^5$ ms$^{-1}$ in the presence of electric field $\vec{E}$ and magnetic field $\vec{B}$. To keep the particle moving in a horizontal direction, it is necessary that: (1) $\vec{B}$ should be perpendicular to the direction of velocity and $\vec{E}$ should be along the direction of velocity. (2) Both $\vec{B}$ and $\vec{E}$ should be along the direction of velocity. (3) Both $\vec{B}$ and $\vec{E}$ are mutually perpendicular and perpendicular to the direction of velocity. (4) $\vec{B}$ should be along the direction of velocity and $\vec{E}$ should be perpendicular to the direction of velocity. Which one of the following pairs of statements are possible?
Two polaroids $P_1$ and $P_2$ are placed with their axis perpendicular to each other. Unpolarised light $I_o$ is incident on $P_1$. A third polaroid $P_3$ is kept in between $P_1$ and $P_2$ such that its axis makes an angle $45^\circ$ with that of $P_1$. The intensity of transmitted light through $P_2$ is
The calculated spin only magnetic moment of $Cr^{2+}$ ion is
An element X has the following isotopic composition: $^{200}$X: 90% $^{199}$X: 8.0% $^{202}$X: 2.0% The weighted average atomic mass of the naturally-occurring element X is closest to:
For a parallel beam of monochromatic light of wavelength $\lambda$, diffraction is produced by a single slit whose width $a$ is much greater than the wavelength of the light. If $D$ is the distance of the screen from the slit, the width of the central maxima will be:
Select the correct match: (1) Haemophilia - Y linked (2) Phenylketonuria - Autosomal dominant trait (3) Sickle cell anaemia - Autosomal recessive trait, chromosome-11 (4) Thalassemia - X linked
A particle mass m, charge Q, and kinetic energy T enter a transverse uniform magnetic field of induction $\vec{B}$. After 3 sec the kinetic energy of the particle will be:
Identify the substances having glycosidic bond and peptide bond, respectively in their structure:
Which of the following compounds has a higher hydration energy than the lattice energy?