Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

In which colour an yellow coloured dress would appear when viewed through a blue filter?

  1. yellow

  2. blue

  3. black

  4. green
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yellow light is a combination of red and green light. A dress appears yellow if it reflects red and green light to our eyes. In order to reflect red and green light, these two primary colors of light must be present in the incident light.
So, blue colored filter allows only blue color and absorbs all the remaining colors.
Therefore, yellow colored dress appears black.

Multiple choice physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

An ultrasound equipment work at frequency:

  1.  Higher than $20,000 Hz $

  2.  Higher than $10,000 Hz $

  3.  Lower than 4420,000 Hz $

  4.  Lower than $10,000 H _2 $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. ultrasound devices operate with frequencies from 20000 Hz up to several gigahertz.

Multiple choice physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

Select the correct statement from the following

  1. Electromagnetic waves cannot travel in vaccum

  2. Electromagnetic waves are longitudinal waves

  3. Electromagnetic waves are produced by charges moving with uniform velocity.

  4. Electromagnetic waves carry both energy and momentum as they propagate through space.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electromagnetic waves are transverse waves that do not require a medium to travel, and they carry energy and momentum. Charges moving with uniform velocity produce constant electric and magnetic fields, but electromagnetic waves are produced by accelerating charges.

Multiple choice physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

A standard radio broadcasting station has an assigned frequency between $535$ and $1605\ kHz$. The VHF(very high frequency) television stations (channels $2$ to $13$) have frequencies between $54$ and $216\ MHz$, while the UHF (u=ultra) stations (channels $14$ to $83$) have frequencies between $470$ and $890\ MHz$. What is the wavelength corresponding to each of the frequencies mentioned?

  1. $9.31, 0.368, 0.773$

  2. $1,39, 0.341, 1.66$

  3. $1.39, 0.638, 0.337$

  4. $None of these$
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

One requires 2 IeV of energy to dissociate a carbon molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dis-acceleration lines is 

  1. visible region

  2. interacted region

  3. ultraviolet region

  4. microwave region
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$E = 21 eV = 21 \times 1.6 \times 10^{-19}$

$\alpha = \dfrac{21 \times 1.6 \times 10^{-19}}{6.62 \times 10^{-34}} = 5.07 \times 10^{15} Hz$
This is belongs ultraviolet region

Multiple choice physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

Neglecting reduced mass effects, what optical transition in the ${ He }^{ + }$ spectrum would have the same wavelength as the first Lyman transition of hydrogen ($n=2$ to $n=1$)

  1. $n = 2$ to $n = 1$

  2. $n = 3$ to $n = 1$

  3. $n = 4$ to $n = 2$

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

The Rydberg formula for hydrogen-like ions is 1/lambda = R * Z^2 * (1/n1^2 - 1/n2^2). For hydrogen (Z=1), the Lyman transition n=2 to n=1 is 1/lambda = R(1 - 1/4) = 3R/4. For He+ (Z=2), the transition n=4 to n=2 gives 1/lambda = R * 2^2 * (1/4 - 1/16) = R * 4 * (3/16) = 3R/4. Thus, they have the same wavelength.

Multiple choice physics spectra the electromagnetic spectrum electromagnetic spectrum electromagnetic waves

The rms value of the electric filed of a plane electromagnetic wave is 720 V/m.The average energy density of electric field and the average energy density are 

  1. $4.58*{ 10 }^{ -6 }{ Jm }^{ -3 };2.15*{ 10 }^{ -7 }{ Jm }^{ -3 }$

  2. $4.3{ 10 }^{ -7 }{ Jm }^{ -3 };8.6{ 10 }^{ -7 }{ Jm }^{ -3 }$

  3. $2.15{ 10 }^{ -7 }{ Jm }^{ -3 };4.3{ 10 }^{ -7 }{ Jm }^{ -3 }$

  4. $8.6{ 10 }^{ -7 }{ Jm }^{ -3 };4.3{ 10 }^{ -7 }{ Jm }^{ -3 }$
Reveal answer Fill a bubble to check yourself
A Correct answer