Light is an electromagnetic wave whose oscillations are perpendicular to the direction of propagation, so it is transverse.
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A string is stretched between fixed points separated by 75.0 cm. It is observed to have resonant frequencies of 420 Hz and 315 Hz. There are no other resonant frequencies between these two. The lowest resonant frequency for this string is
Resonant frequencies are integer multiples of the fundamental; 420/315 = 4/3 so the lower corresponds to n=3, thus f1 = 315/3 = 105 Hz.
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The time period of a simple pendulum is 7 s when the experiment is performed inside a stationary lift. If the lift accelerates upwards with an acceleration of g/8, then the period of the simple pendulum will
Polaroid glass polarises light and an ideal polarizer transmits half the intensity of unpolarised light, so sunglasses use them to reduce glare and intensity.
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A uniform rope of length 10 m and mass 5 kg hangs vertically from a rigid support. A block of mass 2 kg is attached to the free end of the rope. If a transverse wave pulse is produced at the lower end of the rope, the velocity of the pulse at a distance of 1 m from the lower end of the rope in metre per second is:
Wave speed v = sqrt(T/μ); at 1 m from lower end tension = (block mass + 0.5 kg rope segment)g = 2.5g and μ = 0.5 kg/m, so v = sqrt(2.5g/0.5)=sqrt(5g)=7 m/s (using g ≈ 9.8 m/s² gives 7 m/s).
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If length of second pendulum becomes four times, then its time period will become
Period T ∝ √L, so if L becomes 4L, T becomes 2T (two times).
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The adjoining figure shows a glass plate placed vertically on a horizontal table with a beam of unpolarised light falling on its surface at the polarising angle 57° with the normal. The electric vector in the reflected light on the screen S will vibrate with respect to the plane of incidence in a
At Brewster's angle the reflected light is polarized with its electric vector perpendicular to the plane of incidence; for a vertical plane of incidence this means horizontal vibration.
