NEW
Font size
WorksheetsElectrical Science Cat 3 DMEL 245
Total questions: 20
Worksheet time: 10mins
Ohm's Law relates voltage (V), current (I), and resistance (R). Which is correct?
V = I × R
V = R ÷ I
R = Power × V
I = Power × R
An ideal voltage source is characterized by:
Zero voltage
Zero internal resistance
Infinite internal resistance
Variable voltage
In a transformer, mutual induction enables operation. What principle does this describe?
Static induction
Mutual induction
Electrostatic induction
Self induction
Power factor (PF) in AC systems is defined as:
True power ÷ Apparent power
Apparent power ÷ True power
Real power × Reactive power
Resistance ÷ Reactance
According to Kirchhoff's Voltage Law (KVL), the sum of voltages around a closed loop equals:
Conservation of energy
Conservation of charge
Zero
Both A and C
Which component is considered passive?
Transistor
Diode
Resistor
MOSFET
In gases and liquids, current consists of the flow of:
Only electrons
Positive and negative ions
Only positive ions
None
Lenz's Law is used to determine the direction of:
Electric field
Magnetic field
Induced current
Electric potential
What is the RMS value of a sine-wave current?
Peak × 0.5
Average × 1.11
Peak ÷ √2
Peak × √2
Which statement is true for semiconductors?
They're linear
They can be analyzed with Ohm's law
They have both electron and hole currents
They only pass current one way
What is leakage flux in a transformer?
The flux linking both primary and secondary
The flux linking the primary only
The flux outside the core
The flux lost as heat
Why are transformers rated in kVA instead of kW?
Voltage is independent of power factor
Heat losses are expressed in kVA
They depend on apparent, not real power
They can't supply real power
In an equivalent transformer circuit without core losses, what component represents the magnetizing branch?
Rc alone
Xm alone
Xm in series with Rc
Rc in parallel with Xm
What phenomenon causes hysteresis loss in a transformer core?
Eddy currents in windings
Changing direction of magnetic particles
Leakage flux in windings
Capacitive coupling
What does Lenz's Law indicate about induced EMF?
It creates a current aiding the change
It opposes the cause of the flux change
It sets current direction randomly
It maximizes energy output
Which law mathematically expresses induced EMF?
Coulomb's law
Faraday's law
Ampère's law
Ohm's law
What is form factor for an AC waveform?
Peak / Average
RMS / Average
Peak / RMS
Average / RMS
What is the slip in an induction motor?
Rotor speed minus synchronous speed
Synchronous speed minus mechanical load
RPM difference between phases
Difference between input and output torque
What is the purpose of CT (Current Transformer)?
Step-down voltage for measurement
Step-up voltage for transmission
Step-down current for metering
Measure earth fault currents
Which theorem states that any linear two-terminal circuit can be simplified to a voltage source and resistance in series?
Norton's theorem
Millman's theorem
Thevenin's theorem
Superposition theorem
