CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Motors
What energy conversion occurs in an electric motor?
A. Heat to mass
B. Mechanical energy to electrical energy only
C. Chemical energy to light only
D. Electrical energy to mechanical energy
Correct Answer: D
Motors use electromagnetic forces to produce motion.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electromagnetism
Which scientist's law states that induced emf is related to the rate of change of magnetic flux?
A. Boyle
B. Newton
C. Faraday
D. Pascal
Correct Answer: C
Faraday's law is central to generators and transformers.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electromagnetism
What is electromagnetic induction?
A. Heating due to friction
B. Production of an emf when magnetic flux through a circuit changes
C. Flow of water through a pipe
D. Static charging only
Correct Answer: B
Faraday's law links changing magnetic flux to induced emf.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electromagnetism
Which rule helps determine the magnetic-field direction around a straight current-carrying wire?
A. Archimedes' principle
B. Hooke's law
C. Right-hand grip rule
D. Snell's law
Correct Answer: C
The curled fingers of the right hand indicate magnetic-field direction when the thumb points with conventional current.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electromagnetism
How can the strength of a simple electromagnet usually be increased?
A. Use no core and no current
B. Reduce current to zero
C. Increase current or number of coil turns
D. Remove the coil
Correct Answer: C
More ampere-turns generally produce a stronger magnetic field.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electromagnetism
What is an electromagnet?
A. A permanent magnet with no current
B. A battery only
C. A magnet produced by electric current, often using a coil around a ferromagnetic core
D. A resistor
Correct Answer: C
Current through a coil can create a controllable magnetic field.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electromagnetism
What is produced around a current-carrying conductor?
A. No field
B. A magnetic field
C. A vacuum
D. Only a gravitational field
Correct Answer: B
Electric current creates a magnetic field around the conductor.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electric Current
What is direct current (DC)?
A. Current with no charge movement
B. Current that reverses direction periodically
C. Only current in gases
D. Current that flows predominantly in one direction
Correct Answer: D
DC maintains a consistent polarity and direction of charge flow.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electric Current
In conventional current direction, current is considered to flow from which terminal externally?
A. No direction is defined
B. Positive to negative
C. From ground to sky
D. Negative to positive only
Correct Answer: B
Conventional current is defined opposite to electron drift in metallic conductors.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electric Current
What instrument is used to measure electric current?
A. Voltmeter
B. Ammeter
C. Barometer
D. Thermometer
Correct Answer: B
An ammeter is connected in series to measure circuit current.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electric Current
Which equation relates current I, charge Q and time t?
A. I = m/v
B. I = Q/t
C. I = V×R
D. I = P×t
Correct Answer: B
Current equals charge transferred divided by elapsed time.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electric Current
What is the SI unit of electric current?
A. Ohm
B. Watt
C. Volt
D. Ampere
Correct Answer: D
The ampere is the SI base unit of electric current.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Electric Current
What is electric current?
A. Rate of flow of electric charge
B. Energy per unit charge
C. Mass per unit volume
D. Force per unit area
Correct Answer: A
Current measures how much charge passes a point per unit time.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Conductors & Insulators
What is a semiconductor?
A. A mechanical switch only
B. A perfect conductor
C. A material whose electrical conductivity lies between that of conductors and insulators and can be controlled
D. A perfect insulator always
Correct Answer: C
Semiconductors such as silicon have controllable conductivity and underpin electronics.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Conductors & Insulators
What is the main function of an insulator around a wire?
A. To generate electricity
B. To increase current without limit
C. To store data
D. To reduce unwanted current flow and protect users from electric shock
Correct Answer: D
Insulation confines current to the conducting core and improves safety.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Conductors & Insulators
Why are metals generally good conductors?
A. They contain delocalized electrons that can move through the lattice
B. They have no resistance
C. They contain no protons
D. They are always magnetic
Correct Answer: A
Mobile conduction electrons carry charge through metals.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Conductors & Insulators
Which material is commonly used as an electrical insulator?
A. Copper
B. Aluminum
C. Rubber
D. Silver
Correct Answer: C
Rubber has very few mobile charge carriers under ordinary conditions.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Conductors & Insulators
Which material is a good electrical conductor?
A. Rubber
B. Glass
C. Dry wood
D. Copper
Correct Answer: D
Copper has many mobile electrons and low resistivity.
CSS - PMS - CCE - PCS - General Science
Electricity & Magnetism - Conductors & Insulators
What is an electrical conductor?
A. A material that allows electric charge to move relatively easily
B. A substance with no atoms
C. A material that blocks all heat only
D. A material that never contains electrons
Correct Answer: A
Conductors contain mobile charge carriers, such as electrons in metals.
CSS - PMS - CCE - PCS - General Science
Black Holes
What radiation is theoretically emitted by black holes due to quantum effects near the horizon?
A. Hawking radiation
B. Visible light from a solid surface
C. Sound waves
D. Gamma rays from combustion
Correct Answer: A
Hawking's calculation predicts thermal radiation from quantum effects near black-hole horizons.