Physics MCQs

Notes:
A concave lens is a type of lens that has a thinner center than edges, and it is sometimes called a diverging lens because it spreads out light rays that are parallel to its axis. The focal length of a lens is a measure of its ability to focus light, and it is defined as the distance from the lens to the point where the light rays converge. In the case of a concave lens with a power of -5D, the focal length would be equal to 1/5 of a meter, or 20 centimeters.

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Friction is the main reason for any object to come to rest. It is the main reason for the stability of the objects on earth.

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The mean value of the acceleration due to gravity (often denoted as “g”) at Earth’s surface is approximately 9.81 meters per second squared (m/s²). This value represents the average gravitational acceleration experienced by objects on the surface of the Earth. It is important to note that this value is not constant everywhere on Earth’s surface and can vary slightly due to factors such as location, altitude, and the density of the Earth’s crust.

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“Fermi” is the unit of length. The femtometre is an SI unit of length equal to 10⁻¹⁵ metres, which means a quadrillionth of one.

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The north pole of a magnet in a compass points north because it is attracted to the Earth’s magnetic south pole, which is located near Earth’s geographic north pole. The geographic north pole of earth corresponds to magnetic south pole and geographic south pole of earth corresponds to magnetic north pole. The direction in which a compass needle points is known as magnetic north. This is not exactly the direction of the North Magnetic Pole. Instead, the compass aligns itself to the local geomagnetic field, which varies in a complex manner over the Earth’s surface. The angular difference between magnetic north and true north (defined in reference to the Geographic North Pole), at any particular location on the Earth’s surface, is called the magnetic declination. Most map coordinate systems are based on true north, and magnetic declination is often shown on map legends so that the direction of true north can be determined from north as indicated by a compass.

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Ultra High Frequency (UHF) designates the ITU radio frequency range of electromagnetic waves between 300 Megahertz to 3 GHz (3,000 Megahertz).

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When the elevator is slowing down while moving downwards, that means there is an acceleration upwards. The gravitational force must be lesser than the normal force. Thus, during slowing down while moving downwards, the normal force on the feet of a passenger is greater than her weight. In this case the scale will read more than 80 kg.

Notes:
The branch of mechanics which deals with the study of motion of material objects without taking into account the factors which cause motion is called as Kinematics. The branch of mechanics which deals with the study of motion of material objects taking into account the factors which cause motion is called as Dynamics. The branch of mechanics which deals with the study of material objects at rest is called as Statics.

Notes:
The conditions for equilibrium for an object: 1. There is no linear motion of the object i.e. the resultant force on the object is zero 2. There should not be any rotational motion of the object i.e. the torque on the object should be zero 3. The potential energy of the object should be minimum for stable equilibrium.

Notes:
A projectile will achieve maximum horizontal range when it is projected at an angle of 45°. This concept of maximum horizontal range is used by athletes in long jump, javelin throw, cricket ball throw etc