General Science - Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examinations.
1. Consider the following statements:
- It takes approximately 11 seconds for the light to reach the earth from moon
- It takes approximately 8 minutes for the light to reach from the sun.
- It takes 4.22 years for the light to reach from the nearest star Alpha Centauri
Which among the above statements is/ are correct ?
[A] 1 & 2 only
[B] 2 & 3 only
[C] 1 & 3 only
[D] 2 only
Show Answer
Correct Answer: D [2 only]
Notes:
The first statement is incorrect because light takes 1.2 – 1.3 seconds to reach from moon to earth. Second statement is correct. The exact time taken is 8 min 19 seconds (Speed of light=300,000 kilometres per second mean distance of sun from Earth=14,96,00000 Kms . The time comes to be about 498.66 second.) Statement 3 is also incorrect. The first part of the statement is correct which says that It takes 4.22 years for the light to reach from the nearest star, however nearest star is Alpha proxima and not Alpha Centauri is not nearest. Nearest is Proxima Centauri and to reach from Alpha centauri it takes 4.40 years. Next is Barnard`s Star, which is 5.94 light years away from Earth.
2. Which of the following cases amount to be some work done in terms of Physics?
- A man pushing a wall but failing to move it
- A coolie standing with a load of 12 kg on his head
- A boy climbing up a staircase
- A boy carrying a box on his head and sliding over a frictionless horizontal surface
Select the correct option from the codes given below:
[A] Only 2 & 3
[B] Only 3 & 4
[C] Only 1, 3 & 4
[D] Only 3
Show Answer
Correct Answer: D [ Only 3]
Notes:
In case (iii) work is done, because displacement is produced in the direction of applied force. In cases (i), (ii) and (iv), no work is done as no displacement occurs in the direction of applied force.
3. Which of the following is / are correct statements?
- When glass rod is rubbed with silk, negative charge develops on silk
- When Ebonite rod is rubbed with fur, negative charge develops on fur
Select the correct option from the codes given below:
[A] Only 1
[B] Only 2
[C] Both 1 & 2
[D] Neither 1 nor 2
Show Answer
Correct Answer: A [ Only 1]
Notes:
When a glass rod is rubbed with silk, a positive charge develops on the glass rod and a negative charge is developed on silk. The glass rod transfers its electrons to the silk when it is rubbed with silk. Thus, glass rod has less number of electrons than the number of protons in the nucleus. Thus, on the whole, the glass rod gets positively charged. When an ebonite rod is rubbed with fur, a negative charge develops on ebonite rod and a positive charge develops on fur. Ebonite rod gains electrons from the fur when it is rubbed with fur. Thus ebonite has more negative charges as compared to positive charges in the nucleus. Thus, on the whole, ebonite rod gets negatively charged.
4. Which among the following can produce virtual image?
- Converging lens
- Concave Mirror
- Flat Mirror
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 3
[D] 1, 2 & 3
Show Answer
Correct Answer: D [ 1, 2 & 3]
Notes:
Real images can be produced by concave mirrors and converging lenses. But a converging lens and concave mirror are also capable of producing virtual images if the object is within the focal length. Flat mirrors can never produce real image because, rays never really converge.
5. Which of the following is / are correct statements about the Millimeter waves, sometimes seen in news?
- These are among the highest radio frequency band
- They have higher wavelength than Microwaves
- They are most notably used in security appliances
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: C [ Only 1 & 3]
Notes:
Millimeter Waves correspond to the EHF Band which runs the range of frequencies from 30 to 300 gigahertz, above which electromagnetic radiation is considered to be low (or far) infrared light, also referred to as terahertz radiation. This band has a wavelength of ten to one millimetre. The Microwaves have wavelength of from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz. Thus statement 2 is incorrect.
6. If we look at the floating piece of iceberg on the sea, approximately what fraction of it is visible above the seawater level?
[A] 1/8th
[B] 1/6th
[C] 1/10th
[D] 1/5th
Show Answer
Correct Answer: A [ 1/8th]
Notes:
Approximately 1/8 (12.5 %) of the ice is visible above water and 7/8 (87.5 %) of the ice is submerged below the surface. This is because ice and snow are less dense than water. Here we must note that if the iceberg is made up of only compact ice, its visible part may be even 1/10th part because the compact part is relatively denser. But the top of the iceberg is usually made up of snow which is not that much compact and that is why the correct answer of this question is 1/8th.
7. Which among the following is / are correct statements?
1. The images produced by Concave Mirrors are always real images
2. The images produced by Flat Mirrors are always virtual images
3. Converging Lens can produce virtual as well as real images
Select the correct option from the codes given below:
[A] Only 1 is correct
[B] Only 2 is correct
[C] Only 1 & 2 are correct
[D] Only 2 & 3 are correct
Show Answer
Correct Answer: D [ Only 2 & 3 are correct]
Notes:
Real images can be produced by concave mirrors and converging lenses. But a converging lens and concave mirror are also capable of producing virtual images if the object is within the focal length. Thus statement 1 is incorrect, while statement 3 is correct. Flat mirrors can never produce real image because, rays never really converge, so statement 2 is correct.
8. You are sitting inside an open vehicle moving with uniform speed. When you throw a stone vertically upwards, the stone will fall__:
[A] Ahead of you
[B] Behind you
[C] Over you
[D] Either ahead or behind of you
Show Answer
Correct Answer: C [ Over you]
Notes:
Uniform speed means no acceleration. If there is no acceleration and the vehicle is moving with uniform speed; the stone will fall over you.
9. Which of the following is / are correct statements about the cosmic rays?
- They are made of charged particles
- They are received on earth mainly from Sun
- They cause Ozone Depletion
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 1 & 3
[C] Only 1
[D] None of them
Show Answer
Correct Answer: B [ Only 1 & 3]
Notes:
Cosmic Rays are made up of positively and negatively charged particles. Cosmic rays may broadly be divided into two categories: primary and secondary. The cosmic rays that originate from astrophysical sources are primary cosmic rays; these primary cosmic rays interact with interstellar matter creating secondary cosmic rays. Sun is not the major source but is a minor source. The Sun also emits low energy cosmic rays associated with solar flares. The third statement is correct. The chain of reactions in the upper atmosphere due to the cosmic rays causes depletion of the ozone but this depletion is small in comparison to the depletion caused by CFCs.
10. Two pieces of ice at 0°C would freeze together if pressed against each other and then released. In this context, which among the following is the correct principle in action in this?
[A] The melting point of pure ice decreases with pressure.
[B] The melting point of pure ice increases with Pressure
[C] The melting point of pure ice first increases, then decreases with pressure
[D] The melting point of pure ice first decreases then increases with pressure
Show Answer
Correct Answer: A [ The melting point of pure ice decreases with pressure.]
Notes:
Melting point of pure ice decreases with pressure at the rate of 0.0072°C per atmosphere and this is called regulation, which was discovered by Faraday and occurs at some 0°C or very slightly less temperature.
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