Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice various types of barometer fluids physics

If the mass of the sheet at the top of the aneroid barometer used as an altimeter is increased, what will be the effect on the reading?

  1. It will reduce.

  2. It will increase.

  3. No effect.

  4. Can't be determined
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

If the top sheet in an aneroid barometer is heavier, it will displace lesser. So, it gives reading corresponding to a lower pressure with a lighter thin sheet. Lower pressure is observed at more heights and hence, the reading of the altimeter will increase.

Multiple choice various types of barometer fluids physics

Water vaporizes under vacuum conditions. Mark the statement which is correct with respect to using water as a barometric fluid.

  1. It will show the true atmospheric pressure.

  2. It will be clearly seen in the glass tube.

  3. It will not show true atmospheric pressure.

  4. None
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

WATER VAPORISES UNDER VACUUM CONDITIONS.THUS WATER BAROMETER WILL NOT SHOW TRUE ATMOSPHERIC PRESSURE.

Multiple choice various types of barometer fluids physics

Atmospheric pressure at a certain place is equivalent to $78cm$ of mercury. That place is

  1. $250m$ above sea level
  2. $250m$ below sea level
  3. $125m$ above sea level

  4. at the sea level
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Atmospheric pressure at that place is $78cm$ of mercury.
We know that the atmospheric pressure at the sea level is $76cm$ of mercury.
This means, this place has an atmospheric pressure $(78-76)cm=2cm$ more than the atmospheric pressure at the sea level.
We know that the atmospheric pressure increases by $1cm$ for every $125m$ decrease in height.
So, this place is $(125 \times 2)m=250m$ below sea level.

Multiple choice various types of barometer fluids physics
Gradual fall in the mercury level in a barometer indicates

  1. possibility of rain

  2. possibility of thunderstorm

  3. fair weather

  4. dry and sunny weather
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Gradual fall in the mercury level occurs at low pressure- If there is too much moisture in the air, indicates the possibility of rain

Multiple choice various types of barometer fluids physics

Which is the most accurate instrument to measure pressure and is used as a standard?

  1. Aneroid Barometer

  2. Mercury Barometer

  3. Barograph

  4. Manometer
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Answer is B

In the mercury barometer, atmospheric pressure balances a column of mercury, the height of which can be precisely measured. To increase their accuracy, mercury barometers are often corrected for ambient temperature and the local value of gravity.

Multiple choice luminous intensity measurements physics

In the interference pattern, energy is

  1. created at the position of maxima

  2. destroyed at the positions of minima

  3. conserved but is redistributed

  4. not conserved
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

conserved but is redistributed

Multiple choice luminous intensity measurements physics

A lamp placed 60 cm from a screen produces the same illumination as a standard 100 W lamp placed 90 cm away on the other side of the screen. The luminous intensity of the first lamp is 

  1. $49.44W$
  2. $44.44W$
  3. $54.44W$
  4. $34.44W$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

For same illumination $\dfrac{Power} { r^{2}}$ will be same


=> $\dfrac {100} { 0.9^{2}} = \dfrac {P} {0.6^{2}}$
=> P = $44.44 W$

Multiple choice luminous intensity measurements physics

Light has a wave nature, because-

  1. the light travel in a straight line

  2. Light exhibits phenomenon of reflection and refraction

  3. Light exhibits phenomenon interference

  4. Light exhibits phenomenon of photo electric effect.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Interference is a phenomenon unique to wave motion, where waves superimpose to form a resultant wave of greater, lower, or the same amplitude. Reflection and refraction can be explained by both wave and particle models, while the photoelectric effect supports the particle nature.

Multiple choice luminous intensity measurements physics

Light with energy flux 36$\mathrm { w } / \mathrm { cm } ^ { 2 }$ is incident on a well polished metal slate of side 2$\mathrm { cm }$ . Theforce experienced by it is

  1. 0.96$\mu N$
  2. 0.24$\mu N$
  3. 0.12$\mu N$
  4. 0.36$\mu N$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The force exerted by light on a surface is F = P/c, where P is the power (energy flux * area). For a perfectly reflecting surface, F = 2IA/c. For an absorbing surface, F = IA/c. Assuming absorption, F = (36 W/cm^2 * 4 cm^2) / (3 * 10^8 m/s) = 144 / 3 * 10^-8 N = 4.8 * 10^-7 N = 0.48 uN. If reflected, it is 0.96 uN. Given the answer 0.96 uN, the metal plate is considered a perfect reflector.

Multiple choice luminous intensity measurements physics

If relative luminosity is $0.65$ then the luminous flux of a $10 W$ source is

  1. $12130.6$
  2. $4125.5$
  3. $4352.5$
  4. $4452.5$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Luminous flux of a 10W source=Relative luminosity$\times$ luminous flux of 555nm source of 10W

=$0.65\times (685\times 10)=4452.5$