Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics propagation of sound waves sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

The ratio $(v)$ of velocities of sound in dry air and humid air is

  1. $v<1$
  2. $v>1$
  3. $v=1$

  4. Zero
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Because water molecules have less mass than the average air molecules $(N _2 (28 \text{amu}),$ while water $H _2O (18 amu)).$ But It will happen if and only if the pressure is unchanged. Given that dry and humid air are both under the same pressure then we have smaller density for humid air.
And velocity of sound waves$,v,$ in a medium is given by,


$v=\sqrt{\dfrac{\gamma E}{d}}$, here $\gamma = \dfrac{C _P}{C _V}$, 

$E$ is elasticity of the medium, and $d$ is the density.

Since, density of air decreases with humidity increases. therefore velocity of sound increases in humid air.
Option "A" is correct.

Multiple choice physics sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

A rope length $\displaystyle l$ and mass $\displaystyle m$ hanges freely from the ceiling. The velocity of transverse wave as a function of position $\displaystyle x$ along the rope is proportional to

  1. 1 / $\displaystyle \sqrt x$
  2. $\displaystyle \sqrt x$
  3. $\displaystyle x$
  4. $\displaystyle x^0$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\text{Mass per unit length of rope} =\dfrac{m}{l}$
Mass of rope of length $x =\dfrac { m }{ l } x$
Tension, $T = \dfrac { m }{ l } xg$
Velocity, $v=\sqrt { \dfrac { T }{ m }  } =\sqrt { \dfrac { mgl }{ lm } x }$      which is directly proportional to $\sqrt { x } $

Multiple choice physics vibrations of stretched strings sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

When the stem of a vibrating tuning fork is pressed a sounding board, then

  1. transverse vibrations are communicated through stem to the board.

  2. longitudinal vibrations are communicated through stem to the board

  3. both longitudinal and transverse vibrations are communicated through stem on the board

  4. none of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When the tuning fork is set into vibration, the stem of tuning fork vibrate  up and down with longitudinal vibrations hence, when the stem of a vibrating tuning fork is pressed a sounding board, then longitudinal vibrations are communicated through stem to the board.

Multiple choice physics sound sound as a wave of disturbance vibrations in a tuning fork vibrations in tuning fork

When slinky is stretched out in a horizontal direction and first coils are vibrated horizontally then which waves are generated?

  1. Longitudinal Waves

  2. Transverse Waves

  3. Surface waves

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

Longitudinal Waves are generated when slinky is stretched out in a horizontal direction and first coils are vibrated horizontally 

Multiple choice physics work, energy and power forms of energy and energy conservation energy for everything forms of energy

Geothermal energy is feasible in regions that

  1. Are near the sea

  2. Have thermal plants

  3. Have coal mines

  4. Are over hot spots in the crust
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Geothermal energy relies on heat from the Earth's interior. Regions over hot spots in the crust, where magma is relatively close to the surface, are ideal for tapping into this heat.

Multiple choice physics energy transformations and energy transfers forms of energy and energy conservation energy for everything forms of energy

A charged parallel plate capacitor of distance ($d$) has ${U} _{0}$ energy. A slab of dielectric constant ($K$) and thickness ($d$) is then introduced between the plates of the capacitor. The new energy of the system is given by:

  1. $K{U} _{0}$
  2. ${K}^{2}{U} _{0}$
  3. $\cfrac{{U} _{0}}{K}$
  4. $\cfrac{{U} _{0}}{{K}^{2}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice physics energy transformations and energy transfers forms of energy and energy conservation energy for everything forms of energy

 person trying to lose weight by burning fat lifts a mass of $10kg$ upto a height of $0.5\, m\, with\, in\, 1000$ times. Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up? Fat supplies $3.8 \times 10^7 J$ of energy per kg which is converted to mechanical energy with a $20 \%$ efficiency rate. 

  1. $6.45 \times {10^{ - 3}}kg$
  2. $9.89 \times {10^{ - 3}}kg$
  3. $12.89 \times {10^{ - 3}}kg$
  4. $2.45 \times {10^{ - 3}}kg$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Work done per lift = mgh = 10 * 9.8 * 0.5 = 49 J. Total work for 1000 lifts = 49,000 J. With 20% efficiency, energy required from fat = 49,000 / 0.20 = 245,000 J. Fat energy density = 3.8 * 10^7 J/kg. Mass of fat = 245,000 / (3.8 * 10^7) = 6.447 * 10^-3 kg.

Multiple choice physics wave optics wave behaviour huygens wave theory and wavefront wave propagation (huygens' construction)

Corpuscular theory of light was advanced by

  1. Huygen

  2. Newton

  3. Maxwell

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

$Answer:$ B

The corpuscular theory was largely developed by Sir Isaac newton. Newton's theory remained in force for more than 100 years and took precedence over Huygen's wave front theory, partly because of Newton’s great prestige. When the corpuscular theory failed to adequately explain the diffraction, interference and polarization of light it was abandoned in favour of Huygens' wave theory.