Option “1” is correct. The working principle of a washing machine is based on centrifugation force. The term centrifugal force is used to refer to an inertial force or fictitious force, particular to a particle moving on a circular path that has the same magnitude and dimensions as the force that keeps the particle on its circular path but the point in the opposite direction.
302. Parameters of electricity supply in India are-
1. Potential Difference of 220 V, Frequency of 50 hertz and Current Rating of 5A/15A
2. Potential Difference of 150 V, Frequency of 40 hertz and Current Rating of 10 A
3. Potential Difference of 220 V, Frequency of 60 hertz and Current Rating of 15A
4. Potential Difference of 220 V, Frequency of 40 hertz and Current Rating of 5 A
Option “1” is correct. Parameters of electricity supply are different in different countries. In India they are: Potential Difference of 220 V, Frequency of 50 hertz and Current Rating of 5A/15A.
303. Human eye is most sensitive to visible light of the wavelength
1. 655 nm
2. 555 nm
3. 455 nm
4. 755 nm
Option “2” is correct. Eye is most sensitive to yellow-green light that is light of wavelength 555nm.
304. The wave length extension of visible light is-
1. Between 200–900 nm
2. Between 250–850 nm
3. Between 300–800 nm
4. Between 390–780 nm
Option “4” is correct. Visible light is that part of electromagnetic radiation which can be seen by human eyes. A normal human eye can see the electromagnetic radiation between 390–780 nm of wavelength.
305. The term MB is used for-
1. Magnetic Bits
2. Mega Bytes
3. Mega Bits
4. None of the above
Option “2” is correct. The group of 8 bits is called one byte and at least two bits are combined together to form a binary word. MB is used as an abbreviation for Mega byte.
306. X-ray was invented by:
1. W.C.Rontgen
2. Gutenberg
3. Edison
4. Graham Bell
Option “1” is correct. X-ray was invented by W.C.Rontgen .
307. In a pressure cooker food is cooked in shorter time because-
1. The boiling point of water increases
2. The boiling point of water decreases
3. The food takes less heat
4. None of the above
Option “1” is correct. The trapped steam increased the atmospheric pressure inside the cooker. At that pressure boiling point of water is increased.
308. Optical fiber works on which of the following principle of light?
1. Reflection
2. Refraction
3. Diffraction
4. Total internal reflection
Option “4” is correct. Optical fibre work on the principle of Total Internal Reflection of Light. In optical fibre, when light traveling in an optically dense medium hits a boundary at a steep angle (larger than the critical angle for the boundary), the light is completely reflected. This is called total internal reflection.
309. Why does water tank appear shallower when viewed from the top?
1. Due to reflection
2. Due to refraction
3. Due to diffraction
4. Due to total internal reflection
Option “2” is correct. Water Tank appears shallower when viewed from the top due to refraction of light. This virtual depth is known as apparent depth.
310. Which colour is formed when Red and Green are mixed?
1. Light blue
2. Yellow
3. White
4. Grey
Option “2” is correct. Yellow colour is formed when Red and Green are mixed.
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