Question

a. Calculate the junction temperature if the power dissipation
is 4W , ambient temperature is 32oC and thermal resistance b/w
junction and ambient temperature is 25 K/W.

b. Calculate the total harmonic distortion if the fundamental
component is 50mV, V2 is 20mV and V3 is 5mV (other components
negligible)

Answer #1

A house temperature is kept at 298 K. Ambient temperature is 279
K. Power of the motor is 1 W. There is a heat flow of 60 kW from
the system. Is the power of the motor used enough? If it is not
enough, how much should it be?

The transimpedance amplifier is used. The responsivity of the
APD (x=1.0) with a junction capacitance of 10 pF, is 0.7 A/W, the
dark current is negligible, and the noise figure is 3 dB. Assume
the temperature is 300 K. Determine the optimum avalanche
multiplication factor for the diode.
a) Calculate the shot noise limited current for the detector
(Assume dark current is small and T = 300 K).
b) The responsivity of the detector is 0.7 A/W. Calculate the
received...

Liquid, pumped through the inside of the pipe, is at a
temperature Ti = 400K and provides a convection
coefficient hi = 450 W/m2-K at the inner
surface of the pipe. The inside and outside radii of the pipe are
r1 = 0.25 m, r2 = 0.31 m. The thermal conductivity of the pipe is
240 W/m-K. The outside radius of the insulation, r3 = 0.35 m. The
thermal conductivity of the insulation is 20 W/m-K. The outside
surface is...

Suppose you walk into a sauna that has an ambient temperature of
50.0 ∘C.
(a) Calculate the rate of heat transfer to you by radiation in
watts, given your skin temperature is 37.0 ∘C, the emissivity of
skin is 0.98, and the surface area of your body is 1.4 m2.
(b) If all other forms of heat transfer are balanced (the net
heat transfer is zero), how much will your body temperature
increase if your mass is 70 kg, and...

A hot plate with a temperature of 60 ° C will be cooled by
adding 50 triangular profile needle blades (k = 243 W / mK) with a
length of 93 mm and 10 mm. According to the ambient temperature 20
C and the heat transfer coefficient on the surface 20 W / m ^ 2 K;
a-) Wing efficiency, b-) Total heat transfer rate (W) from the
wings, c-) Calculate the effectiveness of a wing.

Assuming the Sun radiates as a blackbody at a temperature of
5800 K, calculate the expected surface temperature of the Earth,
assuming that the Earth also acts as a perfect blackbody. Assume
the Earth absorbs an amount of energy proportional to its
cross-sectional area, but radiates as a spherical blackbody. If the
Earth is in thermal equilibrium with outer space, then the energy
received (mostly at visible wavelengths) must equal the amount of
energy re- radiated (mostly) in the infrared....

In a coal fired power plant, a furnance Wall consists
of a 125 mm wide refractory brick and a 125 mm wide insulating
firebrick separated by an air gap as shown in figure. The outside
Wall is covered with a 12 mm thickness of plaster. The inner
surface of Wall is at 1100 °C, and then room temp is 25 °C. The
Heat transfer coefficient from the outside Wall surface to air in
room is 17 W/m^2 K, resistance to...

16a) A triple glazed window consists of 3 clear glass
panes of 4 mm thickness each, separated by two
air cavities of 13 mm each in thickness. The
window area is 1.0 m2
. If the thermal conductivity
of the glass panes is 0.8 W•m-1•K-1 and of the air
cavities is 0.026 W•m-1•K-1 what is the total
thermal resistance of the window?
(A) 2.452 K•W-1
(B) 0.015 K•W-1
(C) 1.015 K•W-1
(D) 6004 K•W-1
16b)A heater provides 305 W of...

An aluminum transmission line with a diameter of 20 mm has an
electrical resistance of R'elec= 2.636 × 10-4 Ω/m and
carries a current of 700 A. The line is subjected to frequent and
severe cross winds, increasing the probability of contact between
adjacent lines, thereby causing sparks and creating a potential
fire hazard for nearby vegetation. The remedy is to insulate the
line, but with the adverse effect of increasing the conductor
operating temperature.
(a) Calculate the conductor temperature...

1. In an industrial process, a tank containing 200 liters of
water at 372 K at a constant pressure is used as a thermal energy
storage device. The device is used to heat a residential space that
is maintained 293 K. There is a negligible change in the volume of
the water. The water is stirred during this process to maintain a
uniformly distributed temperature. During the process, the
convective heat transfer coefficient between the water and the
space is...

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