Free Practice Questions for Physics in General-studies

The power of a lens is calculated in Diopter.

Important Points:

• Power of a lens is a measure of the convergence or divergence, which a lens introduces in the light falling on it. 
• 1 Diopter = 1 meter ^-1(1 D = m^-1).
• The power of a lens of focal length of 1 meter is one diopter. 
• Power of a lens is positive for a converging lens and negative for a diverging lens. 

One horsepower equals to746 watts.

Important Points:

• The amount of energy transferred per unit time is called power.
• Power is a scalar quantity. Its dimensions are [ML²T^–3]. 
• SI unit of power is Watt.
• The unit of power is named after James Watt. Horse – power (hp) is another unit of power. 

Heinrich Rudolph Hertz laid the foundation for the future development of radio, telephone and telegraph. The SI unit of  frequency was named as 'Hertz' as his honour.

Important Points:

• The frequency of oscillation is defined as the number of oscillations per second.

• One oscillation per second is equal to one hertz (Hz).

• The pitch of the sound is determined by frequency.Higher the frequency of sound wave, the higher will be the pitch of sound.

• 1 hertz is equal to 1 s-1. Tone refers to a single frequency sound.

SSC CPO 13/12/2019 (Morning)

IMPORTANT FACTS

Units of length:

• 1 fermi = 1 f = 10^–15 m 
• 1 angstrom = 1 Å = 10^–10 m 
• 1 astronomical unit = 1 AU (average distance of the Sun from the Earth) = 1.496 × 10¹¹ m
• 1 light year = 1 ly= 9.46 × 10¹⁵ m (distance that light travels with velocity of 3 × 10⁸ m s^–1 in 1 year)
• 1 parsec = 3.08 × 10¹⁶ m (Parsec is the distance at which average radius of earth’s orbit subtends an angle of 1 arc second)

SSC CPO 13/12/2019 (Morning)

IMPORTANT FACTS

Units of length:

• 1 fermi = 1 f = 10^–15 m 
• 1 angstrom = 1 Å = 10^–10 m 
• 1 astronomical unit = 1 AU (average distance of the Sun from the Earth) = 1.496 × 10¹¹ m
• 1 light year = 1 ly= 9.46 × 10¹⁵ m (distance that light travels with velocity of 3 × 10⁸ m s^–1 in 1 year)
• 1 parsec = 3.08 × 10¹⁶ m (Parsec is the distance at which average radius of earth’s orbit subtends an angle of 1 arc second)

SSC MTS 22/08/2019(Evening)

IMPORTANT FACTS -

Temperature Conversion Formulas :

• Celsius to Fahrenheit: 

• Celsius to Kelvin:

• Kelvin is the SI unit of temperature.
• Temperature is the measure of hotness or coldness of an object.

Hubble constant( in cosmology) is a constant of proportionality in the relation between the velocities of remote galaxies and their distances.

Important Points:

• It expresses the rate at which the universe is expanding.
• It is denoted by the symbol H₀. 
• Hubble constant is named in honour of Edwin Hubble, the American astronomer.

S.I. unit of Energy is Joule.

Important Points:

• An object with the ability to do work is said to have energy. 
• 1 joule is the amount of energy required to perform one joule of work. 
• Energy exists in nature in a variety of forms, including kinetic energy, potential energy, heat energy, chemical energy, and so on. 
• The mechanical energy of an object is the sum of its kinetic and potential energies.

 Fundamental SI units:

• Length - Meter (m)
• Time - Second (s)
• Amount of substance - Mole (mol)
• Electric current - Ampere (A)
• Temperature - Kelvin (K)
• Luminous intensity - Candela (cd)
• Mass - Kilogram (kg)

SSC MTS 14/08/2019(Afternoon)

IMPORTANT FACTS

ADDITIONAL INFORMATION

Types of forces-

• When the net effect produced by several forces acting on a body is zero, then the forces are said to be balanced forces. Balanced forces can only bring a change in the shape of the body.  
• When the net effect produced by several forces on a body is non-zero, then the forces are said to be unbalanced forces. Unbalanced force makes the body move and changes the state of rest or motion of an object. 

kg ms^-1 is the SI unit of Momentum.

Important Points:

• Momentum(p) of a body is defined to be the product of its mass m and velocity v. 
• It is vector quantity. Its dimension is [MLT^-1]. 
• The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts. 
• The change in the momentum of the body is equals to the impulse.  

1 pound is equal to 16 ounces.

Important Points:

• The imperial system of measurement is  widely used in the United States, Canada, and some other countries.
• In this system, weight is measured in pounds (lb) and ounces (oz).
• One pound is equal to 16 ounces. This means that there are 16 ounces in every pound.
• One pound is equal to 0.45359237 kilograms.
• One ounce is equal to 28.3495231 grams.
• There are 16 ounces in a pound, and 128 ounces in a gallon.

1 horsepower has 746 Watt.

Important Points:

• Power is defined as the rate at which work or energy is done or transferred. 
• A scalar quantity is power. It has the dimensions [ML²T^-3]. 
• Its SI unit is watt, W, and 1 watt equals 1 J/s. 
• The power unit is named after James Watt. 
• Another unit of power is horsepower (hp). 
• This unit is still used to describe the output of automobiles, motorcycles, and other vehicles. 
• Average power is calculated by dividing total energy consumed by total time required.

The SI unit of pressure is the pascal, which is named after Blaise Pascal.

Important Points:

• The SI unit of pressure is the Pascal, which is equal to one Newton per square meter. 
• Pressure is a force exerted over a specific area. It is measured in pascals, which are equal to newtons per square meter.
• Pascal's law states that pressure applied to an enclosed fluid is transmitted throughout the fluid equally in all directions.
• Energy, work, and power are all different quantities, and they do not have SI units named after Blaise Pascal. 
• Energy is the ability to do work, and it is measured in joules.
• Work is the transfer of energy, and it is measured in joules.
• Power is the rate at which work is done, and it is measured in watts.

Odometer is used to measure the speed of the vehicle.

Important Points:

SSC-CPO 14/03/19 (Morning)

IMPORTANT FACTS

ohm is the SI unit of electrical resistance.

Important Points:

• The property of a conductor to resist the flow of charges through it is called Electrical resistance.
• The resistance of a conductor depends directly on its length, inversely on its area of cross-section, and also on the material of the conductor.

Option Explanation:

• Watt is the unit of Power.
• Coulomb is the SI unit of Electric charge.
• Ampere is the SI unit of Electric current.

Bolometer is used to measures infrared radiation.

Important Points:

• Infrared waves are produced by hot bodies and molecules.
• Infrared waves have longer wavelength.
• Infrared waves are used for the therapeutic purpose and long distance.

The power of a lens is measured by Diopter.

Important Points:

• Power of a lens is a measure of the convergence or divergence, which a lens introduces in the light falling on it. 
• 1 Dioptre = 1 metre ^-1(1 D = m^-1). 
• The power of a lens of focal length of 1 metre is one dioptre. 
• Power of a lens is positive for a converging lens and negative for a diverging lens. 
• Kelvin, candela, and Ampere are the SI unit of temperature, luminous intensity, and current respectively.

The SI unit of radioactivity is Becquerel.

Important Points:

• A. H. Becquerel discovered radioactivity. Radioactivity was a nuclear phenomenon in which an unstable nucleus undergoes a decay. 
• This is referred to as radioactive decay. Three types of radioactive decay occur in nature : 
• (i) α-decay in which a helium nucleus ⁴₂He is emitted; 
• (ii) β-decay in which electrons or positrons (particles with the same mass as electrons, but with a charge exactly opposite to that of electron) are emitted; 
• (iii) γ-decay in which high energy (hundreds of keV or more) photons are emitted. 

SSC-CGL 11/06/2019 (Afternoon)

IMPORTANT FACTS