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Physicshelpline

. November 2017

Modern Physics

Q- A 150 W light bulb emits about 8 W of visible light. (The other 142 W are emitted as infrared radiation or lost as heat to the surroundings.) The average wavelength of the visible light is about 510 nm, so make the simplifying assumption that all the visible light has this wavelength.

(a) What i…

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Second Pendulum

Q- A second pendulum is one that moves through its equilibrium position once each second. The period of the pendulum is precisely 2s. The length of a second pendulum is 0.9927 m at Tokyo Japan and 0.9942 m at Cambridge England. What is the ratio of the free-fall accelerations at these two locations?

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Wave-Optics: Polarization

Q- Two polarizing sheets have their transmission axes crossed so that no light gets through. A third sheet is inserted between the first two such that its transmission axis makes an angle θ with that of the first sheet. Unpolarized light of intensity I0 is incident on the first sheet. Find the inte…

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Circular motion: Rolling of a wheel

Q- The position vector of a particle moving on the rim of a rolling wheel in the x-y plane is given by

r = (10t + 5 cos 2t) i + (5 - 5 sin 2t) j, here r is in meters and t is in seconds. i and j are unit vectors in x and y directions respectively.

(a) What are the velocity and speed of the parti…

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