Physics Answers

transformer connected to a 120-V (rms) ac line is to supply 12.0 V (rms) to a portable electronic device. The load resistance in the secondary is 5.00 Ω

Ω

.

(a) What should the ratio of primary to secondary turns of the transformer be?

(b) What rms current must the secondary supply?

(c) What average power is delivered to the load?

(d) What resistance connected directly across the 120-V line would draw the same power as the transformer? Show that this is equal to 5.00 Ω

Ω

 times the square of the ratio of primary to secondary turns.

A graded index fiber with a parabolic index profile supports the propagation of

742 guided modes. The fiber has a numerical aperture in air of 0.3 and a core diameter

of 70 μm. Determine the wavelength of the light propagating in the fiber.

Further estimate the maximum diameter of the fiber which gives single-mode

operation at the same wavelength.

Given 2 containers both filled with water. Container A has hot water while B has cold

one, what will happen to its temperature if you put the 2 containers in close contact?

How pure metals and a semi conductor can be distinguished through the effect of temperature on their electrical resistance

Using the laws of physics and chemistry, explain the reason why certain materials can

conduct heat, while others cannot

Describe the mode of operation of one instrument which uses the radiation heat transfer

mechanism

matter has a body-centered cubic unit cell with a length of 330 𝑝𝑚 along an edge

and a density of 8.57 𝑔 𝑐𝑚−3

. Calculate the atomic mass of the matter.

a) Define viscosity.

b) A matter has a body-centered cubic unit cell with a length of 330 𝑝𝑚 along an edge and a density of 8.57 𝑔 𝑐𝑚−3 . Calculate the atomic mass of the matter.

c) Find the total energy of a moving object of mass 6.3 𝑘𝑔 and momentum 11.5 × 106 𝑘𝑔𝑚𝑠 −1 .

Explain why the angle is important when launching projetiles.

Find the distance travelled when the intial angular velocity is 3 rad/s , the final angular velocity is 25rad/s , the time of motion is 10s.