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. June 2016

Current Electricity

Q- A 2.8 kΩ and a 2.1 kΩ resistor are connected in parallel; this combination is connected in series to a 1.8 kΩ resistor. If each resistor is rated at 0.50 W, what is the maximum voltage that can be applied across the whole network without damaging resistors?

Solution:

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Loudness

Q- A person standing a certain distance from an airplane with four equally noisy jet engines experiences a sound level of 120dB. What sound level intensity would this person experience at double the initial distance when the captain shuts down all but one engine?

Solution:

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Capacitor

(On request - Ravi)

Q- How does the energy stored in a parallel plate capacitor change if:

a) The potential difference is doubled.

b) The separation between the plates is doubled with the capacitor remains connected to the battery.

c) The separation between the plates is doubled after it is disc…

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Elasticity

Q- A steel bar (Ysteel = 210 GPa) and an aluminum bar (Yaluminum) = 10 GPa are bonded together to form the composite bar as shown. Determine the maximum stress in (a) the aluminum, (b) the steel, when the bar is bent towards aluminum bar about a horizontal axis, with a torque M = 60 Nm.

Solution:

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Convex Lens

Q- The projection lens in a certain slide projector is a single thin lens. A slide 24.0 mm high is to be projected so that its image fills a screen 1.80 m high. The slide to screen distance is 3.00m.

a) Determine the focal length of the projection lens.

b) How far from the slide should the lens of…

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Thermal Physics

Q- During a 2.5 hour run the metabolism of a marathon runner generates excessive body heat at an average rate of 4200 KJ per hour. Assume that the body (surface area 2.0 m2) loses heat at a rate of 50 W by convection.

a) Determine the rate at which radiation dissipates heat. Assume a skin temperatu…

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