About this quiz
50 questions covering every section of the note.
This Lok Sewa practice set has 50 multiple-choice questions (Subject: Science and Technology · For: Kharidar, Nayab Subba, Section Officer · Level: Easy). Take the quiz above first; after that, use the study list below to revise every question with its correct answer and a short explanation.
Study list: all 50 questions with answers and explanations
The SI unit of electric current is the:
- A) Ampere ✔
- B) Ohm
- C) Volt
- D) Coulomb
Why: Current is measured in amperes; 1 A is 1 coulomb per second.
An ammeter is connected in a circuit:
- A) In parallel
- B) It is not connected
- C) Across the battery only
- D) In series ✔
Why: An ammeter measures the current through a component, so it is connected in series.
Potential difference is measured by a:
- A) Ammeter
- B) Voltmeter ✔
- C) Galvanometer
- D) Wattmeter
Why: A voltmeter, connected in parallel, measures potential difference in volts.
Ohm's law gives the relation:
- A) P = V × I
- B) Q = I × t
- C) V = I × R ✔
- D) E = P × t
Why: Ohm's law states that V = I × R at constant temperature.
A 12 V battery is connected to a 4 Ω resistor. What current flows?
- A) 48 A
- B) 8 A
- C) 0.33 A
- D) 3 A ✔
Why: I = V ÷ R = 12 ÷ 4 = 3 A.
If the length of a wire is increased, its resistance:
- A) Increases ✔
- B) Decreases
- C) Stays the same
- D) Becomes zero
Why: Resistance is directly proportional to the length of the wire.
Which is the best conductor of electricity?
- A) Copper
- B) Aluminium
- C) Silver ✔
- D) Iron
Why: Silver is the best conductor, but copper is used for wires because it is cheaper.
Silicon and germanium are examples of:
- A) Conductors
- B) Semiconductors ✔
- C) Insulators
- D) Superconductors
Why: Silicon and germanium are semiconductors used in chips, diodes and transistors.
The filament of an electric bulb is made of:
- A) Copper
- B) Tungsten ✔
- C) Nichrome
- D) Aluminium
Why: Tungsten has a very high melting point, so it can glow white-hot without melting.
Household appliances are connected:
- A) In series
- B) Only through a transformer
- C) In a single loop
- D) In parallel ✔
Why: Parallel wiring gives each appliance the same voltage and lets each be switched separately.
Two 6 Ω resistors are connected in parallel. What is the total resistance?
- A) 3 Ω ✔
- B) 6 Ω
- C) 12 Ω
- D) 36 Ω
Why: 1/R = 1/6 + 1/6 = 2/6, so R = 3 Ω.
The commercial unit of electrical energy (one unit) is the:
- A) Watt
- B) Kilowatt
- C) Kilowatt-hour ✔
- D) Joule
Why: Electricity bills count energy in kilowatt-hours; 1 kWh is one unit.
How many units of electricity does a 100 W bulb use in 10 hours?
- A) 0.1 unit
- B) 10 units
- C) 1 unit ✔
- D) 100 units
Why: 100 W × 10 h = 1,000 Wh = 1 kWh = 1 unit.
A fuse wire should have:
- A) Low melting point ✔
- B) High melting point
- C) Zero resistance
- D) Very large thickness
Why: A fuse must melt quickly when the current is too high, so it has a low melting point.
The frequency of the household AC supply in Nepal is:
- A) 220 Hz
- B) 60 Hz
- C) 100 Hz
- D) 50 Hz ✔
Why: Nepal's supply is about 230 V at 50 hertz.
A transformer works on:
- A) DC only
- B) AC only ✔
- C) Both AC and DC equally
- D) Neither
Why: A transformer needs a changing magnetic field, which only AC produces.
Which of these is NOT attracted by a magnet?
- A) Iron
- B) Nickel
- C) Cobalt
- D) Copper ✔
Why: Copper is non-magnetic; iron, nickel and cobalt are magnetic materials.
A freely suspended bar magnet always comes to rest in which direction?
- A) East-west
- B) Up-down
- C) North-south ✔
- D) Any direction
Why: Because of the Earth's magnetic field, a freely hanging magnet points north-south.
Who discovered electromagnetic induction in 1831?
- A) Michael Faraday ✔
- B) Ohm
- C) Oersted
- D) Volta
Why: Michael Faraday showed that a changing magnetic field produces a current, the principle of generators.
An electric motor changes:
- A) Mechanical energy into electrical energy
- B) Electrical energy into mechanical energy ✔
- C) Heat into electricity
- D) Light into electricity
Why: A motor turns electrical energy into motion; a generator does the opposite.
The SI unit of electric current is:
- A) Ampere ✔
- B) Volt
- C) Ohm
- D) Watt
Why: Current is measured in amperes.
The SI unit of potential difference is:
- A) Volt ✔
- B) Ampere
- C) Coulomb
- D) Joule
Why: Voltage is measured in volts.
The SI unit of resistance is:
- A) Ohm ✔
- B) Volt
- C) Ampere
- D) Henry
Why: Resistance is measured in ohms (Ω).
The SI unit of electric charge is:
- A) Coulomb ✔
- B) Ampere
- C) Volt
- D) Farad
Why: Charge is measured in coulombs.
The SI unit of electric power is:
- A) Watt ✔
- B) Joule
- C) Volt
- D) Kilowatt-hour
Why: Power is measured in watts.
Ohm's law states:
- A) V = IR ✔
- B) P = IR
- C) V = I/R
- D) R = VI
Why: Voltage equals current times resistance.
If V = 12 V and R = 4 Ω, the current is:
- A) 3 A ✔
- B) 48 A
- C) 8 A
- D) 16 A
Why: I = V/R = 12/4 = 3 A.
Electric power can be calculated as:
- A) P = VI ✔
- B) P = V/I
- C) P = I/R
- D) P = R/V
Why: Power = voltage × current.
The commercial unit of electrical energy (one "unit") is:
- A) Kilowatt-hour ✔
- B) Watt
- C) Joule
- D) Volt-ampere
Why: 1 unit = 1 kWh.
A 100 W bulb used for 10 hours consumes:
- A) 1 unit ✔
- B) 10 units
- C) 0.1 unit
- D) 100 units
Why: 100 W × 10 h = 1000 Wh = 1 kWh.
The instrument that measures current is the:
- A) Ammeter ✔
- B) Voltmeter
- C) Galvanometer only
- D) Barometer
Why: An ammeter is connected in series to measure current.
The instrument that measures potential difference is the:
- A) Voltmeter ✔
- B) Ammeter
- C) Thermometer
- D) Hydrometer
Why: A voltmeter is connected in parallel.
An ammeter is connected in a circuit in:
- A) Series ✔
- B) Parallel
- C) Either way
- D) Not connected
Why: All the current must pass through it.
Household appliances are connected in:
- A) Parallel ✔
- B) Series
- C) Mixed only
- D) Single loop
Why: Parallel wiring gives each device full voltage and independent switching.
In a series circuit, the total resistance is:
- A) The sum of all resistances ✔
- B) Less than the smallest resistance
- C) Always zero
- D) The product of resistances
Why: R = R1 + R2 + R3…
In a parallel circuit, the total resistance is:
- A) Less than the smallest single resistance ✔
- B) The sum of resistances
- C) Greater than the largest resistance
- D) Always equal to one resistor
Why: 1/R = 1/R1 + 1/R2…
A good conductor of electricity is:
- A) Copper ✔
- B) Rubber
- C) Glass
- D) Plastic
Why: Copper has many free electrons.
A material that does not allow current to flow is an:
- A) Insulator ✔
- B) Conductor
- C) Semiconductor
- D) Superconductor
Why: Rubber, glass and plastic are insulators.
A fuse wire protects a circuit by:
- A) Melting when current is too high ✔
- B) Increasing voltage
- C) Storing charge
- D) Producing magnetism
Why: It has a low melting point and breaks the circuit.
The normal household supply voltage in Nepal is about:
- A) 220–230 V ✔
- B) 110 V
- C) 12 V
- D) 440 V
Why: Nepal uses about 230 V, 50 Hz AC.
The frequency of AC supply in Nepal is:
- A) 50 Hz ✔
- B) 60 Hz
- C) 100 Hz
- D) 25 Hz
Why: Nepal's grid runs at 50 hertz.
A device that changes AC voltage up or down is a:
- A) Transformer ✔
- B) Generator
- C) Motor
- D) Rectifier
Why: Transformers work only with AC.
A device that changes mechanical energy into electrical energy is a:
- A) Generator (dynamo) ✔
- B) Motor
- C) Battery
- D) Transformer
Why: Generators work on electromagnetic induction.
Electromagnetic induction was discovered by:
- A) Michael Faraday ✔
- B) Isaac Newton
- C) Thomas Edison
- D) Alessandro Volta
Why: Faraday discovered it in 1831.
The magnetic effect of electric current was discovered by:
- A) Hans Christian Oersted ✔
- B) Faraday
- C) Ohm
- D) Ampere
Why: Oersted noticed a compass needle move near a current (1820).
Like magnetic poles:
- A) Repel each other ✔
- B) Attract each other
- C) Do nothing
- D) Become neutral
Why: North repels north, south repels south.
The north pole of a freely hanging magnet points towards:
- A) Geographic north ✔
- B) Geographic south
- C) East
- D) West
Why: That is why compasses show direction.
A temporary magnet made by passing current through a coil around iron is an:
- A) Electromagnet ✔
- B) Permanent magnet
- C) Bar magnet
- D) Natural magnet
Why: It is magnetic only while current flows.
A device that converts AC into DC is a:
- A) Rectifier ✔
- B) Transformer
- C) Inverter
- D) Generator
Why: Rectifiers use diodes to give DC.
The safety wire connected to the metal body of appliances is the:
- A) Earth wire ✔
- B) Live wire
- C) Neutral wire
- D) Fuse wire
Why: Earthing carries leakage current safely to the ground.