Study HubHubPage 30/118Scan verified MCQs with the answer highlighted, then open explanations when you want the reasoning.
Read Mode
Quantum Mechanics
A photon is always considered to be: ________?
A photon is a particle of light and always moves at the speed of light in vacuum, which is approximately 3 x 10^8 m/s. It cannot be at rest or move at any other speed such as the speed of sound.
Read Mode
Rotational Motion
Relation between linear velocity and angular velocity:
The linear velocity (v) of a point on a rotating object is related to its angular velocity (ω) and radius (r) by the formula v = rω. This means the linear speed increases with both the radius and the angular velocity.
Read Mode
Antiparticles
The antiparticle of the electron is: ______?
The antiparticle of the electron is the positron, which has the same mass as the electron but opposite charge. Protons, mesons, and neutrons are different particles and not the electron's antiparticle.
Read Mode
Black Body Radiation
A black body emitting all the radiation in the visible region appears ________.
A black body that emits radiation across the entire visible spectrum appears white because white light is a combination of all visible wavelengths. Therefore, the correct answer is White.
Read Mode
Orbital Mechanics
Earth’s orbital speed is __________?
Earth's average orbital speed around the Sun is approximately 30 km/s, which is the widely accepted and measured value.
Read Mode
Rotational Motion
If the axis of rotation passes through the body and the body moves around itself, then the motion is called:
When a body rotates about an axis passing through itself, the motion is called spin motion. Orbital motion involves rotation around an external point, rectilinear motion is straight-line motion, and translatory motion refers to movement without rotation.
Read Mode
Radiation Detection Instruments
Which instrument is used to detect the path of visible rays?
A Wilson Cloud Chamber (Cloud Detector) is used to visualize the paths of charged particles, including visible rays, by creating condensation trails in supersaturated vapor. Geiger counters and solid state detectors detect radiation but do not visually show the path of rays.
Read Mode
Electric Current
A potential difference is applied across the ends of a wire. If the potential difference is doubled, then the drift velocity of free electrons will:
The drift velocity of free electrons in a wire is directly proportional to the applied potential difference (voltage). Therefore, if the potential difference is doubled, the drift velocity will also double.
Read Mode
Resistivity And Resistance
A wire of uniform cross-sectional area A, length L, and resistance R is cut into two parts. The resistivity of each part:
Resistivity is a material property and does not depend on the dimensions of the wire. Cutting the wire into parts changes the resistance but not the resistivity, which remains the same for each part.
Read Mode
Vectors
Which of the following is the reverse process of the composition of vectors?
The composition of vectors involves combining vectors to form a resultant vector, typically through addition. The reverse process is the resolution of vectors, which breaks a single vector into its component vectors.