Explanation

• Cathode rays consist of negatively charged particles called electrons.
• Opposite charges attract each other, so negatively charged cathode rays are attracted towards the positively charged plate.
• This deflection proves that cathode rays carry a negative electric charge.

Last verified on 02-11-2026

Explanation

Explanation

• Charles' Law states that the volume of a fixed amount of gas is directly proportional to its absolute temperature when pressure remains constant.
• The formula is V1 / T1 = V2 / T2, where temperature is measured in Kelvin.
• When the temperature increases, the gas volume increases; when the temperature decreases, the volume decreases, provided the pressure remains constant.

Last verified on 28-10-2026

Explanation

• Density is the mass per unit volume of a substance.
• Density is calculated by dividing the mass of a substance by its volume.
• The SI unit of density is kilogram per cubic metre (kg/m³).

Last verified on 25-10-2026

Explanation

• The reactivity of alkali metals increases down Group 1 of the periodic table.
• Potassium reacts more vigorously with cold water than lithium and sodium.
• The reaction produces potassium hydroxide and hydrogen gas, releasing heat that may ignite the hydrogen.

Last verified on 01-11-2026

Explanation

Explanation

• Destructive interference occurs when two waves meet and their displacements cancel each other.
• It occurs when the path difference is an odd multiple of half the wavelength.
• Complete cancellation occurs when the waves have equal amplitudes and are exactly opposite in phase.

Last verified on 31-10-2026

Explanation

Explanation

• In longitudinal waves, particles of the medium vibrate parallel to the direction of wave propagation.
• These waves consist of compressions and rarefactions.
• Sound waves in air are a common example of longitudinal waves.

Last verified on 31-10-2026

Explanation

Given:

Object distance (u) = 30 cm

Focal length (f) = 15 cm

2 x f = 2 x 15 = 30 cm

So object is at 2F.

Lens formula:

1/f = 1/v + 1/u

1/15 = 1/v + 1/30

1/v = 1/15 - 1/30

1/v = 1/30

v = 30 cm

Image also forms at 30 cm on other side.

Magnification = v / u = 30 / 30 = 1

Magnification 1 means image size = object size.

Answer: The same - inverted and same size.

Last verified on 31-10-2026