Which of the following quantities consists of SI unit as WATT ?
A. Force
B. Charge
C. Current
D. Power
The SI unit of power is the watt and it is discover by the Scottish Engineer James Watt. Power is the rate of consumption of electric energy. So, it is equivalent to joules per second.
Which of the following has no units?
A. Permeability
B. Moment of a magnet
C. Magnetic susceptibility
D Permittivity
Magnetic susceptibility is the degree to which a material is magnetized by an external magnetic field, hence in the SI system it is dimensionless.
Which quantity consists of a unit 1KWh ?
A. Energy
B. Time
C. Power
D. Charge
1 kWh is the amount of energy used by a 1 kW (1000 watt) resistance for 1 hour. Energy = Power × Time.
Which quantity should be measured by the voltmeter ?
A. Current
B. Voltage
C. Power
D. Speed
Voltmeter is a high resistance device used for measuring potential difference or voltage. It must be connected in parallel for measurement
Internal resistance of ideal current source is ?
A. zero
B. infinite
C. finite
B. 100 ohms
Ideal current source delivers energy at specified current, which is independent on voltage across the load. The internal resistance must become very high to deliver maximum current.
Internal resistance of ideal voltage source is ?
A. zero
B. infinite
C. finite
D. 100 ohms
Internal resistance of ideal voltage source is
Capacitor does not allow the sudden change of ?
A. current
B. voltage
C. power
D. None of the above
The expression of current through a capacitor is
For sudden change of voltage infinite current is required. But practically it is not possible.
Practical capacitor circuit has finite value of time constant
Inductor does not allow the sudden change of
A. current
B. voltage
C. power
D. None of the above
Voltage developed across an inductor is expressed bY
Sudden change of current means di will change at dt → 0 (dt tends to zero), so sudden change of current means infinite voltage. Therefore it is not possible.
Power dissipation in ideal inductor is
A. Maximum
B. Minimum
C. Zero
D. A finite value
Internal resistance of ideal inductor is zero. As there is no resistance, there should not be any dissipation of power. Pure inductor has no resistive component, so it active power dissipation is zero.
Which of the following are the passive elements?
A. Resistor
B. Bulb
C. Both
D. None of these.
When the element is not capable of delivering energy independently, are called as passive element. Both resistor and bulb are the passive elements and they can’t increase the energy level of a circuit