DC Circuits Quiz

If a resistance to which a constant voltage is applied is halved, what power dissipation will result?

• Doubled

• Halved

• Stays the same

• Quadrupled

If the reference point is changed to the earth point then any voltage taken w.r.t. the earth is known as

• Absolute potential

• Earth ground

• Relative voltage

• Absolute point

What is the significance of connecting loads in parallel?

• It makes power consumption less

• It provides greater efficiency

• It increases the safety factor

• It allows independent operations of loads

Which of the following safety rules should be observed while working on live electric circuit?

• Keep yourself well insulated from earth ground.

• When making measurements in a live circuit place one hand behind your back or in your pocket.

• Make resistance measurements only in a live circuit.

• Both A and B.

Under the maximum power transfer condition, what is the power absorbed by the load resistance R_L?

• 526 W

• 562 W

• 625 W

• 652 W

The hot resistance of an incandescent lamp is about _____ times its cold resistance.

• 10

• 50

• 5

• 100

If a resistor in a series circuit is shorted, the series current, I,

• decreases

• stays the same.

• increases.

• drops to zero.

The equivalent wye element of 3 equal resistors each equal to R and connected in delta is

• R

• R/3

• 3/2 R

• 3R

A coil of aluminum wire has a resistance of 50 Ω when its temperature is 0°C. Determine its resistance at 100°C if the temperature coefficient of resistance of aluminum at 0°C is 0.0038/°C.

• 69 Ω

• 65 Ω

• 96 Ω

• 90 Ω

A certain factory takes 250 A at 220 V. It is supplied through a pair of feeders 73.2 meters long and 1.29 cm² in cross section. What voltage must be maintained at the supply end of the feeders? (Use ρ = 1.78 μΩ-cm)

• 111.5 V

• 222.5 V

• 333.5 V

• 444.5 V