A transformer is used to light 100 W 25 volt lamp from 250 Volt ac mains. The current in the main cable is 0.5 A. Calculate the efficiency of the transformer.
A lens immersed in a transparent liquid is not visible. Under what condition can this happen?
1 Crore+ students have signed up on EduRev. Have you? Download the App 
The power in an AC circuit contains an inductor of 30 mH, a capacitor of 300 μF, a resistor of 70 Ω, and an AC source of 24 V, 60 Hz. Calculate the energy dissipated in the circuit in 1000 s.
In a stepdown transformer, the number of turns in the secondary coil is 20 and the number of turns in the primary coil is 100. If the voltage applied to the primary coil is 120 V, then what is the voltage output from the secondary coil?
How many types of spherical refracting surfaces are there?
A boy uses spectacles of focal length 50 cm. Name the defect of the vision he is suffering from.
The speed of the yellow light in a certain liquid is 2.4 × 10^{8} m/s. Find the refractive index of the liquid.
In Young’s doubleslit experiment with monochromatic light, how is fringe width affected, if the screen is moved closer to the slits?
Which among the following is a portion of a transparent refracting medium bound by one spherical surface and the other plane surface?
How much intensity of the image is increased if the diameter of the objective of a telescope is doubled?
The wavelength of light coming from a sodium source is 589 nm. What will be its wavelength in the water?
In Young’s doubleslit experiment, lights of green, yellow, and orange colors are successively used. Write the fringe widths for the three colors in increasing order.
X is thicker in the middle than at the edges, whereas, Y is thicker at the edges than in the middle. Identify ‘X’ and ‘Y’.
A fly is sitting on the objective of a telescope. What will be its effect on the final image of the distant object?
A light wave enters from air into glass. How will the energy of the wave be affected?
In Young’s doubleslit experiment, the two parallel slits are made one millimeter apart and a screen is placed one meter away. What is the fringe separation when bluegreen light of wavelength 500 nm is used?
Which of the following can be chosen to analogously represent the behavior of a particle?
Identify the material whose resistivity lie between 106 Ωm and 104 Ωm.
Two lenses of focal lengths 5 cm and 50 cm are to be used for making a telescope. Which lens will you use for the objective?
If a wave undergoes refraction, what will be the phase change?
What would be the resultant intensity at a point of destructive interference, if there are two identical coherent waves of intensity I0 producing an interference pattern?
A solenoid has core of a material with relative permeability 200 and its windings carry a current of 2 A. The number of turns of the solenoid is 200 per meter. What is the magnetization of the material?
Which of the following is used to increase the range of a telescope?
When a wave undergoes reflection at a denser medium, what will be the phase change?
What happens to the interference pattern if the phase difference between the two sources varies continuously?
How did de – Broglie conclude the modification of Bohr’s II postulate?
According to the thin lens formula, which one of the following is true regarding the focal length of the lens?
A rectangular coil, of sides 4 cm and 5 cm respectively, has 50 turns in it. It carries a current of 2 A, and is placed in a uniform magnetic field of 0.5 T in such a manner that its plane makes an angle of 60o with the field direction. Calculate the torque on the loop.
Which among the following is not attracted by magnets?
Which of the following is not a basic property of magnets.
‘X’ can see objects in the ultraviolet light while human beings cannot do so. Identify X.
A light wave enters from air into glass. How will the frequency of the wave be affected?
What will be the effect on the fringes formed in Young’s doubleslit experiment if the apparatus is immersed in water?
How does the magnifying power of a telescope change on increasing the diameter of its objective?
What would be the resultant intensity at a point of constructive interference, if there are two identical coherent waves of intensity I’ producing an interference pattern?
8 docs148 tests

8 docs148 tests
