Two galaxies with an angular separation at the observer of ` 5.0 × 10^(−4)` radians are observed with a radio telescope. Both galaxies emit radio waves of wavelength `2.5×10^(−2) m`.
The images of the galaxies are just resolved by the telescope. The diameter of the circular collecting dish of the telescope is
A mass oscillates with simple harmonic motion (SHM) of amplitude xo. Its total energy is 16 J.
What is the kinetic energy of the mass when its displacement is `x_0/2`?
Fewer maxima will be observed.
The intensity of the central maximum will increase.
The outer maxima will become narrower.
The width of the central maximum will decrease.
The emission spectrum is then measured by an observer moving away from the gas sample.
What are the correct shifts X* and Y* for spectral lines X and Y?
Light of wavelength `lambda` is incident normally on a diffraction grating that has a slit separation of `(7lambda)/2`. What is the greatest number of maxima that can be observed using this arrangement?
The first principal maximum is observed at an angle θ to the direction of the incident light. The number of slits is increased to 8 each having the same width and spacing as the first 4.
Three statements about the first principal maximum with 8 slits are
I. the angle at which it is observed is greater than θ
II. its intensity increases
III. its width decreases.
Which statements are correct?
I and II only
I and III only
II and III only
I, II and III
At which position is the resultant force on the pendulum bob zero?
At position A
At position B
At position C
Resultant force is never zero during the oscillation
Which of the following changes, carried out separately, in respect of b and D will result in an increase in width of the first diffraction maximum formed on the screen?
red, green, blue
red, blue, green
blue, green, red
green, blue, red
What change will increase θs?
Increase the width of the slit
Decrease the width of the slit
Increase the distance between the slit and the screen
Decrease the distance between the slit and the screen
Replacing the narrow slit with a circular aperture of same size.
Moving the two sources further from the aperture.
Using red light.
Using violet light.
approaching the observer at constant speed.
approaching the observer at increasing speed.
moving away from the observer at constant speed.
moving away from the observer at increasing speed.
A particle is oscillating with simple harmonic motion (shm) of amplitude x0 and maximum kinetic energy Ek. What is the potential energy of the system when the particle is a distance 0.20x0 from its maximum displacement?
Scattering of alpha particles
Reflections from the top and bottom surfaces of the film result in three rays J, K and L. Which of the rays has undergone a phase change of `pi` rad?
J and L only
J and K only
J, K and L
The angle between the first orders is θ1.
What is the wavelength of the light?
`N sin theta_1`
`N sin (theta_1/2)`
The waves have a path difference of `λ/4`. The phase difference between the waves is
The speed of the emitted sound and its wavelength, measured at the source, are `nu and λ` respectively. Which of the following is the wave speed and the wavelength, as measured by the stationary observer?
A moving observer measures the sound as having the frequency f ′. The observer is moving directly away from the source at a speed that is 30% of the speed of sound in air.
Which of the following gives the correct value for `(f′)/f`?
The central maximum of the diffraction pattern of one source must coincide with the central maximum of the diffraction pattern of the other source.
Light from the sources must pass through a circular aperture.
Light from the sources must be coherent.
The first minimum of the diffraction pattern of one source must coincide with the central maximum of the diffraction pattern of the other source.
The light passes through a circular aperture of diameter b and is received by an observer. The angular separation of the sources from the observer’s position is θ. The sources are not resolved by the observer. Which of the following mathematical relationships applies?
`theta <1.22 lambda/b`
`theta >1.22 lambda/b`
`theta =1.22 lambda/b`
where c is the speed of sound in still air. The train emits sound of wavelength λ. What is the observed speed of the sound and observed wavelength as the train approaches?
A source emits sound of wavelength λ0 and wave speed `v_0`. A stationary observer hears the sound as the source moves away. What are the wavelength of the sound and the wave speed of the sound as measured by the stationary observer?
The speed of sound in still air is v. What is the frequency of the sound observed when the ambulance travels at speed `v/10` towards a stationary observer?
The frequency of the sound as measured at the emitter is f. The frequency according to the observer
is always greater than f.
is always equal to f.
is always less than f.
varies during the journey.
A body moves with simple harmonic motion (SHM) with period T and total energy ET. What is the total energy when the period of the motion is changed to 5T and the amplitude of the motion remains constant?
Two point sources of light have an angular separation of θ, as measured by a distant observer. The light passes through a circular aperture of radius r just before reaching the observer. Which of the following conditions must be true for the two sources to be resolved?
`theta <0.61 lambda/r`
`theta <1.22 lambda/r`
`theta >=0.61 lambda/r`
`theta >=1.22 lambda/r`
observed wavelength of the sound is less than the emitted wavelength.
observed wavelength of the sound is greater than the emitted wavelength.
speed of sound relative to the observer has decreased.
speed of sound relative to the observer has increased.
The blue light is now replaced by red light. What additional change is needed so that the lines of constructive interference remain in the same angular positions?
Make the slits wider
Make the slits narrower
Move the slits closer together
Move the slits further apart
A train moves at constant speed whilst emitting a sound wave of frequency f0. At t=t0 the train passes through a station. Which graph shows the variation with time t of the frequency f of the sound wave as measured by an observer standing on the station platform?
`2 lambda/bquad radians.`
`2 lambda/bquad degrees.`