Physics - Study Mode
[#786] Which process allows water to enter the atmosphere?
Correct Answer
(D) Evaporation
Explanation
Solution: Evaporation is the process that allows water to enter into the atmosphere. Sunlight turns liquid water into water vapor which then rises higher into the atmosphere and forms into clouds. Plants, too, help water get into the atmosphere through a process called transpiration.
[#787] Which is a correct way to measure wavelength?
Correct Answer
(A) Nearest peak to peak
Explanation
Solution: Wavelength of a wave can be measured with the distance between two nearest crest and crest or nearest troughs. It is measured as armstrong units.
[#788] If the phase difference between two points is 120° for a wave with velocity of 360 m/s and frequency 500 Hz, then path difference between the two points is
Correct Answer
(D) 24 cm
Explanation
Solution: If v is the wave velocity and f is the frequency, wavelength is given by: λ = v/f So as per the question, λ = 360/500 = 0.72 The path difference between two points is given by λ/2π × φ = 0.72/360 × 120 = 0.24 m = 24 cm
[#789] Why are we able to hear short wave broadcasts better than long wave broadcasts ?
Correct Answer
(A) Short waves are more energetic than long waves.
Explanation
Solution: Short waves are more energetic than long waves. Short waves are unaffected by atmospheric disturbances. By convention, short waves are meant for long distances whereas long waves are reserved for short distances.
[#790] The frequency of ultrasound wave is typically
Correct Answer
(A) Above 20 kHz
Explanation
Solution: Ultrasound refers to a sound wave with a frequency greater than the upper limit of human hearing, which is generally over 20 kHz. In general, humans can hear sounds with a frequency between 20 Hz and 20 kHz.