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WorksheetsBEKG 2433 for BMFG S4&5
Total questions: 10
Worksheet time: 20mins
The difference between alternating current (AC) and direct current (DC) is:
AC changes value and DC does not
AC changes direction and DC does not
Both answer (a) and (b)
Neither answer (a) nor (b)
A sine wave with a period of 2ms is changing at a faster rate than a sine wave with a period of:
1.5ms
1.0ms
0.0025s
0.0015s
If the peak value of a sine wave is 10V, the peak-to-peak value is
1V
12V
40V
20V
The instantaneous value of a 15A peak sine wave at a point 32° from its positive-going zero crossing is
7.9A
7.5A
15.0A
13.5A
If the peak value of a sine wave is 20V, the rms value is
15.15V
14.14V
14.45V
10.0V
Two series resistors are connected to an ac source. If there are 6.5Vrms across one resistor and 3.2Vrms across the other, the peak source voltage is
13.72V
9.70V
9.19V
4.52V
Convert each of the following to the polar form
5 + j20
10.32<15.96°
20.12<75.96°
30.62<75.96°
20.62<75.96°
A certain sine wave has a positive-going zero crossing at 0° and an rms value of 20V. Calculate its instantaneous value at each of the following angles:
a. 110°
b. 250°
a) 26.57 V
b) -26.58 V
a) 16.37 V
b) -16.88 V
a) 22.52 V
b) -16.18 V
a) 20.13 V
b) -22.34 V
A coil having a resistance of 10W and an inductance of 0.1H is connected across a 100 V, 50 Hz supply. Determine:
a) The reactance and the impedance of the coil
b) The current flow
c) The phase different between the current and the applied voltage
(51.78W, 52.89W, 3.13A, 12.35°)
(30.42W, 38.97W, 3.03A, 72.35°)
(11.22W, 31.57W, 3.13A, 12.35°)
(31.42W, 32.97W, 3.03A, 72.35°)
A single-phase motor takes 30A at a power factor of 0.65 lagging from a 240V, 50 Hz supply. A capacitor is connected in parallel to correct the power factor to unity.
Calculate the value of the supply current after power factor correction. Make your answer easy to read. Example: 10.5V or 10.50V
19.5A
19.50A
19.49A
19.48A
19.5 A
