General Science - Physics MCQs

Notes:
A photograph can be recorded using lens and normal light sources but in case of holography, laser is required and the light from the object is scattered directly onto the recording medium. After cutting of a photograph, each piece shows half of the scene but in holography, each piece shows the whole scene.

Notes:
The first statement is correct. The wavelength of X-Rays is from 0 Å to 250Å. The Hard X-rays have a wavelength of less than 10Å while the soft X-Rays have the wavelength of more than 10Å. The second statement is incorrect because Both Electric and Magnetic fields don’t affect X-Rays. The Third statement is incorrect because X-Rays show most properties of light.

Notes:
Real images can be produced by concave mirrors and converging lenses. But a converging lens and concave mirror are also capable of producing virtual images if the object is within the focal length. Flat mirrors can never produce real image because, rays never really converge.

Notes:
Approximately 1/8 (12.5 %) of the ice is visible above water and 7/8 (87.5 %) of the ice is submerged below the surface. This is because ice and snow are less dense than water. Here we must note that if the iceberg is made up of only compact ice, its visible part may be even 1/10th part because the compact part is relatively denser. But the top of the iceberg is usually made up of snow which is not that much compact and that is why the correct answer of this question is 1/8th.

Notes:
Refraction is a phenomenon of light, sound wave, water wave by which the direction of a wave changed while passing from one medium to another. Some of the examples of refraction are Mirage, appearing of raised coin in a trough filled with water, bent pencil in glass of water, rainbow, dispersion of light sunset, etc.

Notes:
The first statement is correct. Signal quality is a lot superior in FM than AM because the amplitude based signals are more susceptible to noise than those which use frequency. Further, the noise signals are difficult to filter out in AM reception whereas FM receivers easily filter out noise using the capture effect and pre-emphasis, de-emphasis effects. In capture effect, the receiver locks itself to catch stronger signal so that signals received are more synced with that at the transmitting end.
In pre-emphasis, de-emphasis process, the signal is further amplified to a higher frequency at sending end (pre-emphasis) and vice versa at receiver end (de-emphasis). These two processes reduce down the chances of a signal to get mixed with other signals and make FM more immune to noise than AM.
The third statement is also correct. AM waves work in the range of KHz while in FM waves work in MHz range. As a result, AM waves have a higher wavelength than the FM ones. A higher wavelength increases the range of AM signals as compared to FM which have a limited area of coverage.

Notes:
Uniform speed means no acceleration. If there is no acceleration and the vehicle is moving with uniform speed; the stone will fall over you.

Notes:
The first statement is correct. When a liquid freezes, it releases thermal energy into its immediate environment. But the second statement is incorrect, because a solid must absorb thermal energy in order to melt. Third statement is also incorrect because while a substance undergoes a phase change, its temperature remains constant. This implies that as a solid melts or as a liquid freezes, its temperature remains constant.

Notes:
VHF (Very High Frequency) omnidirectional radio range (VOR), is a short-range radio navigation system for aircraft, enabling aircraft to determine their position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons, with a receiver unit. Uses radio frequencies in the very high frequency (VHF) band from 108 to 117.95 MHz. VOR is the standard air navigational system in the world, used by both commercial and general aviation.

Notes:
While PSLV is a four stage vehicle, GSLV is three stage vehicle. You may read this if you want.