SPSC Assistant (Sindh, BS-16) Everyday Science Physics — Set 3

1. Question 1

   Q1. When a constant force is applied to a body, it moves with uniform ______.

   • A) momentum
   • B) velocity
   • C) speed
   • D) acceleration

   Answer: acceleration

   Explanation: Newton's second law states F = ma; when a constant net force is applied, the acceleration is constant (uniform), meaning the object's velocity changes at a steady rate.

2. Question 2

   Q2. The magnifying power of a simple microscope can be increased by:

   • A) Increasing the focal length of the lens
   • B) Decreasing the focal length of the lens
   • C) Using a lens of large aperture
   • D) Using a lens of short aperture

   Answer: Decreasing the focal length of the lens

   Explanation: Magnifying power of a simple microscope = 1 + D/f (where D = 25 cm, f = focal length); decreasing f increases the magnifying power, so a shorter focal length lens produces greater magnification.

3. Question 3

   Q3. An instrument that detects the presence of an electric current is called an:

   • A) Electroscope
   • B) Endoscope
   • C) Manometer
   • D) Electroencephalograph

   Answer: Electroscope

   Explanation: A galvanometer is the precise instrument for detecting current, but an electroscope can detect the presence of electrical charge/potential; in some exam contexts "electroscope" is accepted for current detection.

4. Question 4

   Q4. The units of electricity (kWh) consumed by a 2500-watt air-conditioner in one hour are:

   • A) 2.5 units
   • B) 0.25 units
   • C) 2.25 units
   • D) 25 units

   Answer: 2.5 units

   Explanation: Energy (kWh) = Power (kW) × Time (h) = 2.5 kW × 1 h = 2.5 units.

5. Question 5

   Q5. A common unit used for gas billing related to energy content is:

   • A) BTU
   • B) Pascal
   • C) Joule
   • D) None of these

   Answer: BTU

   Explanation: BTU is the scientifically accurate choice. The concept tested here is core everyday science for MDCAT, ECAT, and general ability papers.

6. Question 6

   Q6. A semi-conductor is a substance whose ability to conduct current lies in between:

   • A) Conductors and insulators
   • B) Conductors and superconductors
   • C) Insulators and superconductors
   • D) Wood and plastic

   Answer: Conductors and insulators

   Explanation: Semiconductors (e.g., silicon, germanium) have electrical conductivity between that of conductors (metals) and insulators, which can be modulated by doping or temperature.

7. Question 7

   Q7. The energy possessed by water in a dam is:

   • A) Electrical energy
   • B) Kinetic energy
   • C) Potential energy
   • D) Mechanical energy

   Answer: Potential energy

   Explanation: Water held behind a dam is elevated above its natural level, giving it gravitational potential energy (PE = mgh) that converts to kinetic energy when released.

8. Question 8

   Q8. What is the unit for measuring the energy requirements of a human body?

   • A) Erg
   • B) Joule
   • C) Kilowatt
   • D) Calorie

   Answer: Calorie

   Explanation: The calorie (kilocalorie) is the unit used to express the energy content of food and the energy requirements of the human body for metabolic processes.

9. Question 9

   Q9. Which one of the following units represents the largest amount of energy?

   • A) Calorie
   • B) Joule
   • C) Erg
   • D) Electron volt

   Answer: Calorie

   Explanation: 1 calorie = 4.184 joules, 1 joule = 10⁷ ergs, and 1 electron volt = 1.6×10⁻¹⁹ joules; therefore a calorie represents the largest amount of energy among these units.

10. Question 10

    Q10. A lightning flash and thunderbolt occur at one and the same time.

    • A) The light is seen after the sound is heard
    • B) The sound is heard at the same time as the light is seen
    • C) The light is seen first and the sound is heard afterwards
    • D) Sometimes light is seen first and sometimes sound is heard first

    Answer: The light is seen first and the sound is heard afterwards

    Explanation: Light travels at 300,000 km/s while sound travels at ~343 m/s in air; lightning (light) is seen almost instantly while thunder (sound) arrives seconds later.

11. Question 11

    Q11. Which of the following is used as a coolant in nuclear reactors?

    • A) Heavy water
    • B) Cadmium
    • C) Liquid sodium
    • D) Graphite

    Answer: Liquid sodium

    Explanation: Liquid sodium is used as a coolant in liquid metal fast breeder reactors (LMFBRs) due to its excellent heat transfer properties and high boiling point (~883°C).

12. Question 12

    Q12. The power of a supercomputer is measured in terms of:

    • A) MIPS
    • B) BIPS
    • C) TIPS
    • D) FLOPS

    Answer: FLOPS

    Explanation: Supercomputer performance is measured in FLOPS (Floating Point Operations Per Second), with modern machines reaching petaFLOPS or exaFLOPS.

13. Question 13

    Q13. One horsepower is equal to how many Watts?

    • A) 820 Watts
    • B) 780 Watts
    • C) 760 Watts
    • D) 746 Watts

    Answer: 746 Watts

    Explanation: One mechanical horsepower is defined as exactly 746 watts (≈0.746 kW), based on James Watt's measurements of work done by a horse.

14. Question 14

    Q14. Who discovered the force of attraction or repulsion?

    • A) Faraday
    • B) Van der Waals
    • C) Coulomb
    • D) None of these

    Answer: Coulomb

    Explanation: Coulomb is the scientifically accurate choice. The concept tested here is core everyday science for MDCAT, ECAT, and general ability papers.

15. Question 15

    Q15. Why are transformers used in the transmission of electric power?

    • A) Because they speed up transmission
    • B) Because they can conserve electrical energy
    • C) Because they can reduce transmission losses
    • D) Because they help to distribute electrical energy efficiently

    Answer: Because they can reduce transmission losses

    Explanation: Transformers step up voltage for long-distance transmission; since Power = I²R, higher voltage means lower current, which dramatically reduces resistive heat losses in cables.

16. Question 16

    Q16. Cylindrical lenses are advised for a patient suffering from:

    • A) Hypermetropia
    • B) Myopia
    • C) Astigmatism
    • D) Night blindness

    Answer: Astigmatism

    Explanation: Astigmatism is caused by an irregular curvature of the cornea or lens; cylindrical (toric) lenses compensate for this irregularity by focusing light differently in different meridians.

17. Question 17

    Q17. Which one of the following colours has the longest wavelength?

    • A) Yellow
    • B) Blue
    • C) Red
    • D) Green

    Answer: Red

    Explanation: In the visible spectrum, red light has the longest wavelength (approximately 620-750 nm), while violet has the shortest.

18. Question 18

    Q18. A light-year is a unit of:

    • A) Time
    • B) Energy
    • C) Distance
    • D) Mass

    Answer: Distance

    Explanation: A light-year is the distance that light travels in one year in a vacuum - approximately 9.46 trillion kilometers - making it a unit of distance, not time.

19. Question 19

    Q19. The energy needed to fuel essential body processes is called:

    • A) Essential nutrient level
    • B) Basal metabolism
    • C) Recommended daily allowance
    • D) None of these

    Answer: Basal metabolism

    Explanation: Basal metabolism is the scientifically accurate choice. The concept tested here is core everyday science for MDCAT, ECAT, and general ability papers.

20. Question 20

    Q20. Electromagnetic wave was discovered by Heinrich Rudolf Hertz. He was _______?

    • A) French
    • B) English
    • C) German
    • D) Polish

    Answer: German

    Explanation: Heinrich Rudolf Hertz was a German physicist who first conclusively proved the existence of electromagnetic waves predicted by Maxwell's equations, in the late 1880s.