DC circuits Flashcards
If a resistance to which a constant
voltage is applied is halved, what
power dissipation will result?
doubled
If the reference point is changed to
the earth point then any voltage taken
w.r.t. the earth is known as
Absolute potential
What is the significance of
connecting loads in parallel?
It allows independent
operations of loads
Two ac sources feed a common
variable resistive load as shown in
figure. Under the maximum power
transfer condition, what is the power
absorbed by the load resistance RL?
625 W
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.
The hot resistance of an incandescent
lamp is about _____ times its cold
resistance.
10
. If a resistor in a series circuit is
shorted, the series current, I,
increases.
The equivalent wye element of 3
equal resistors each equal to R and
connected in delta is
R/3
A coil of aluminum wire has a
resistance of 50 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 ohms
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 = 1.78 -cm)
222.5 V
A wire with a smaller cross-sectional
area will produce:
more heat
Halving the cross-sectional area of a
conductor will:
Double the resistance.
An aluminum wire has a resistance of
50 at 20°C. The wire is heated to a
temperature of 100°C. Determine the
resistance of the wire at 100°C,
assuming that the temperature
coefficient of resistance at 0°C is
0.004/°C
64.81 ohms
In Norton’s Theorem, the short
circuit current is obtained by
shorting the load terminals
Delta to wye or wye to delta
transformation technique is applied
to a ______ network.
three-terminal
If the diameter of a wire is doubled,
its current carrying capacity becomes
four times
If a resistance element is part of two
loops, how many voltage drops must
be calculated for that component?
two
20 ohms - [20 ohms||20 ohms] - 10 ohms
10 ohms
In a series circuit, the current, I, is
the same everywhere.
. Suppose you double the voltage in a
simple dc circuit and cut the
resistance in half. The current will
become:
Four times as great
When a material becomes a
superconductor, its resistivity
becomes
zero
“The sum of the emf’s and potential
differences around a closed loop
equals zero” is a consequence of:
Conservation of energy
Two (2) 115-V incandescent lamps A
and B are connected in series across a
230-V source. If lamp A is rated 75
watts and lamp B is rated 50 watts,
determine the current drawn by the
series connection.
0.52 A
Which of the following is neither a
basic physical law nor derivable from
one?
. Ohm’s law
