Electricity & Magnetism — Practice Test/Quiz
25 multiple-choice questions. Select an option for each question. Click Check Score to reveal right/wrong answers and explanations.
1. Who discovered the link between electricity and magnetism?
A) Michael Faraday
B) James Clerk Maxwell
C) Hans Christian Ørsted
D) Alessandro Volta
Correct: C) Hans Christian Ørsted. In 1820 Ørsted showed that an electric current produces a magnetic field around a wire.
2. How many poles does an electromagnet have?
A) One
B) Two
C) Three
D) Four
Correct: B) Two. An electromagnet, like a bar magnet, has a north and a south pole.
3. Which of the following appliances use electromagnets?
A) Electric bell
B) Mixer grinder
C) Loudspeaker
D) All of these
Correct: D) All of these. Electromagnets are used in bells, motors, speakers and other appliances.
4. The strength of an electromagnet can be changed by changing the —
A) Shape of core
B) Color of wire
C) Number of coil turns or current
D) Type of insulation
Correct: C) Number of coil turns or current. More turns or more current increases the magnetic field.
5. The direction of an electromagnet can be changed by changing the —
A) Material of core
B) Direction of current
C) Thickness of wire
D) Length of wire
Correct: B) Direction of current. Reversing current reverses north and south poles.
6. How do migratory birds, fish and some animals navigate across continents?
A) By stars only
B) By the Sun only
C) By sensing Earth's magnetic field
D) By wind direction
Correct: C) By sensing Earth's magnetic field. Many species use magnetoreception for navigation.
7. Why does Earth behave like a giant magnet?
A) Because of water in oceans
B) Because of molten iron and nickel in its core
C) Because of rotation only
D) Because of atmosphere
Correct: B) Because of molten iron and nickel in its core. Their motion produces electric currents that create Earth's magnetic field.
8. When the same current flows through a nichrome wire and a copper wire, which becomes hotter?
A) Copper
B) Nichrome
C) Both equally
D) None
Correct: B) Nichrome. Nichrome has higher resistance and converts more electrical energy into heat.
9. What is electrical resistance?
A) Flow of charge
B) Opposition to current flow
C) Energy of electrons
D) Type of conductor
Correct: B) Opposition to current flow. Resistance (measured in ohms) opposes the flow of electric current.
10. When current flows through a conductor, it produces —
A) Light only
B) Sound
C) Heat
D) None
Correct: C) Heat. The heating effect of current converts part of electrical energy to thermal energy.
11. The heat generated in a wire when current flows depends on —
A) Material only
B) Thickness only
C) Length only
D) Material, thickness, length and duration of current
Correct: D) All of these. Heat depends on resistance (material, length, thickness) and how long current flows.
12. Why does a conductor get heated when current passes through it?
A) Because electrons stop moving
B) Because moving electrons collide with atoms
C) Because current decreases
D) Because of magnetic force
Correct: B) Collisions between electrons and atoms convert electrical energy into heat.
13. Which devices work on the heating effect of current? (Choose the correct list)
A) Electric iron, heater, geyser, toaster
B) Fan, refrigerator, bulb, TV
C) Speaker, battery, bell, motor
D) Generator, switch, wire, magnet
Correct: A) Iron, heater, geyser, toaster — these convert electrical energy to heat.
14. What is e-waste?
A) Food waste
B) Electronic waste
C) Energy waste
D) Water waste
Correct: B) Electronic waste — discarded electronic devices like phones, computers and TVs.
15. Which device generates electricity by chemical reactions?
A) Motor
B) Battery (cell)
C) Transformer
D) Magnet
Correct: B) Battery. Cells/batteries convert chemical energy into electrical energy via reactions.
16. The solution used in a voltaic cell is called —
A) Electrolyte
B) Catalyst
C) Solvent
D) Reactant
Correct: A) Electrolyte. It contains ions and allows current by ion movement.
17. A current-carrying coil behaves like —
A) Resistor
B) Capacitor
C) Magnet
D) Battery
Correct: C) Magnet. A coil with current produces a magnetic field like a bar magnet.
18. Today, which type of battery is most commonly used as a rechargeable battery?
A) Lead-acid
B) Nickel-cadmium (NiCd)
C) Lithium-ion
D) Alkaline
Correct: C) Lithium-ion. Widely used in phones, laptops and electric vehicles.
19. Scientists are working on which type of battery for the future?
A) Air battery
B) Solid-state battery
C) Wet-cell battery
D) Zinc-carbon
Correct: B) Solid-state battery. It uses a solid electrolyte and aims for better safety & energy density.
20. In a dry cell, the carbon rod is the —
A) Negative electrode (anode)
B) Positive electrode (cathode)
C) Separator
D) Electrolyte
Correct: B) Positive electrode. The carbon rod acts as the cathode; the zinc container acts as the anode.
21. Which of the following metal pairs can be used to make a voltaic cell?
A) Zinc / Copper
B) Iron / Plastic
C) Zinc / Wood
D) Silver / Glass
Correct: A) Zinc/Copper. Metal pairs like zinc/copper produce a potential difference due to different reactivities.
22. In a zinc-copper voltaic cell, which metal acts as the positive electrode (cathode)?
A) Zinc
B) Copper
C) Aluminium
D) Magnesium
Correct: B) Copper. Zinc tends to oxidize (negative electrode), copper is reduced (positive electrode).
23. Why do some metals act as positive electrodes while others act as negative electrodes?
A) Because of their color
B) Because of their chemical properties (reactivity)
C) Because of their size
D) Because of their weight
Correct: B) Chemical properties. The tendency to lose or gain electrons (reactivity) decides electrode behavior.
24. Voltaic or Galvanic cells are named after which two scientists?
A) Alessandro Volta and Luigi Galvani
B) Michael Faraday and James Clerk Maxwell
C) Isaac Newton and Albert Einstein
D) Hans Ørsted and Alessandro Volta
Correct: A) Alessandro Volta and Luigi Galvani. Their work led to the names voltaic/galvanic cells.
25. What is a 'dead cell'?
A) A cell that explodes
B) A cell that leaks
C) A cell that no longer produces current
D) A cell that glows
Correct: C) A cell that no longer produces current because its chemical reactants are exhausted.