| 4951 |
The SI unit of inductance is: |
Physics
Self and mutual induction |
Medium |
| 4952 |
If the number of turns of a solenoid is doubled, keeping its length and area the same, its self-inductance be… |
Physics
Self and mutual induction |
Medium |
| 4953 |
The mutual inductance between two coils does NOT depend on: |
Physics
Self and mutual induction |
Hard |
| 4954 |
The peak value of an AC voltage is 325 V. Its RMS value is about: |
Physics
Alternating current |
Easy |
| 4955 |
The reactance of a 0.1 H inductor at 50 Hz is about: |
Physics
Alternating current |
Easy |
| 4956 |
A series LCR circuit has R = 30 Ω, X_L = 80 Ω and X_C = 40 Ω. Its impedance is: |
Physics
Alternating current |
Medium |
| 4957 |
In a purely inductive AC circuit, the current: |
Physics
Alternating current |
Medium |
| 4958 |
As the frequency of the AC supply increases, the reactance of a capacitor: |
Physics
Alternating current |
Hard |
| 4959 |
A series LCR circuit has L = 0.1 H and C = 10 μF. Its resonant frequency is about: |
Physics
Resonance and power in AC circuits |
Medium |
| 4960 |
At resonance in a series LCR circuit, the impedance is: |
Physics
Resonance and power in AC circuits |
Easy |
| 4961 |
The power factor of a purely inductive circuit is: |
Physics
Resonance and power in AC circuits |
Easy |
| 4962 |
A series circuit with R = 30 Ω and Z = 50 Ω is connected to a 200 V (rms) supply. The average power consumed … |
Physics
Resonance and power in AC circuits |
Medium |
| 4963 |
A choke coil is preferred to a resistor for reducing current in AC circuits because the choke: |
Physics
Resonance and power in AC circuits |
Hard |
| 4964 |
A transformer has 200 turns in the primary and 1000 turns in the secondary. If the primary voltage is 220 V A… |
Physics
AC generator and transformer |
Easy |
| 4965 |
An ideal step-down transformer gives 11 V and 4 A from a 220 V supply. The primary current is: |
Physics
AC generator and transformer |
Medium |
| 4966 |
A coil of 100 turns and area 0.02 m² rotates at 50 revolutions per second in a field of 0.1 T. The peak emf i… |
Physics
AC generator and transformer |
Hard |
| 4967 |
A transformer works on the principle of: |
Physics
AC generator and transformer |
Easy |
| 4968 |
In an AC generator, the induced emf in the rotating coil is maximum when the plane of the coil is: |
Physics
AC generator and transformer |
Medium |
| 4969 |
Maxwell's displacement current through a surface is given by: |
Physics
Displacement current |
Easy |
| 4970 |
A parallel-plate capacitor is being charged, and the current in the connecting wires is 1.5 A. What is the di… |
Physics
Displacement current |
Easy |
| 4971 |
The voltage across a 2 μF capacitor increases at a steady rate of 5000 V/s. What is the displacement current … |
Physics
Displacement current |
Medium |
| 4972 |
In a plane electromagnetic wave in vacuum, the peak electric field is 6 V/m. What is the peak magnetic field? |
Physics
Displacement current |
Medium |
| 4973 |
A plane electromagnetic wave travels along the +x axis and its electric field oscillates along the y axis. Al… |
Physics
Displacement current |
Hard |
| 4974 |
Which electromagnetic radiation has the shortest wavelength? |
Physics
Electromagnetic spectrum |
Easy |
| 4975 |
Radar systems used for aircraft navigation mainly use: |
Physics
Electromagnetic spectrum |
Easy |
| 4976 |
An FM station broadcasts at 100 MHz. What is the wavelength of its waves in air? |
Physics
Electromagnetic spectrum |
Medium |
| 4977 |
The ozone layer in the upper atmosphere protects living things mainly by absorbing: |
Physics
Electromagnetic spectrum |
Medium |
| 4978 |
An electromagnetic wave has a frequency of 10 GHz. What are its wavelength and the band it belongs to? |
Physics
Electromagnetic spectrum |
Hard |
| 4979 |
A spherical mirror has a radius of curvature of 24 cm. What is the magnitude of its focal length? |
Physics
Reflection by spherical mirrors |
Easy |
| 4980 |
The image formed by a convex mirror of a real object is always: |
Physics
Reflection by spherical mirrors |
Easy |
| 4981 |
An object is placed 20 cm in front of a concave mirror of focal length 15 cm. Where is the image and what is … |
Physics
Reflection by spherical mirrors |
Medium |
| 4982 |
An object is placed 20 cm in front of a convex mirror of radius of curvature 40 cm. Where is the image? |
Physics
Reflection by spherical mirrors |
Medium |
| 4983 |
A person stands 10 cm from a concave shaving mirror of focal length 15 cm. Which description of the image is … |
Physics
Reflection by spherical mirrors |
Hard |
| 4984 |
The working of an optical fibre is based on: |
Physics
Refraction and total internal reflection |
Easy |
| 4985 |
A water tank is 12 cm deep. Viewed from directly above, how deep does it appear? (Refractive index of water =… |
Physics
Refraction and total internal reflection |
Easy |
| 4986 |
What is the critical angle for light going from a medium of refractive index √2 into air? |
Physics
Refraction and total internal reflection |
Medium |
| 4987 |
Diamond sparkles more than glass cut to the same shape mainly because diamond has: |
Physics
Refraction and total internal reflection |
Medium |
| 4988 |
A point object in air is 30 cm from the convex surface of a large glass block (n = 1.5). The radius of curvat… |
Physics
Refraction and total internal reflection |
Hard |
| 4989 |
What is the power of a concave lens of focal length 25 cm? |
Physics
Lenses |
Easy |
| 4990 |
An object is placed 30 cm in front of a convex lens of focal length 20 cm. What are the image distance and ma… |
Physics
Lenses |
Medium |
| 4991 |
An equiconvex glass lens (n = 1.5) has both radii of curvature equal to 20 cm. What is its focal length? |
Physics
Lenses |
Medium |
| 4992 |
Two thin lenses of power +5 D and –3 D are placed in contact. What is the focal length of the combination? |
Physics
Lenses |
Medium |
| 4993 |
A glass convex lens (n = 1.5) has a focal length of 20 cm in air. What is its focal length when fully immerse… |
Physics
Lenses |
Hard |
| 4994 |
A thin prism of angle 5° is made of glass of refractive index 1.5. What is its deviation of a ray? |
Physics
Prism |
Easy |
| 4995 |
When white light passes through a glass prism, which colour is deviated the most? |
Physics
Prism |
Easy |
| 4996 |
An equilateral glass prism gives a minimum deviation of 30°. What is the refractive index of the glass? |
Physics
Prism |
Medium |
| 4997 |
A ray passes through an equilateral prism at minimum deviation. What is the angle of refraction at the first … |
Physics
Prism |
Medium |
| 4998 |
A thin prism of angle 6° has refractive indices 1.66 for violet and 1.64 for red. What is the angular dispers… |
Physics
Prism |
Hard |
| 4999 |
Why does the objective of an astronomical telescope have a large aperture? |
Physics
Optical instruments |
Easy |
| 5000 |
A convex lens of focal length 5 cm is used as a simple microscope with the image formed at the near point (25… |
Physics
Optical instruments |
Easy |