Explanation

X-rays are a type of electromagnetic radiation that are commonly used in radiotherapy to destroy cancer cells.

They have enough energy to penetrate deep into tissue and damage the DNA of cancer cells, slowing their growth or killing them.

Explanation

Gamma-rays have the highest penetrating power, making them suitable for treating tumors that are deep inside the body.

Gamma-rays are high-energy electromagnetic waves with frequencies higher than X-rays, and they can travel several centimeters into tissue before being absorbed.

Explanation

Sound waves require a physical medium, such as air, water, or solid objects, to propagate.

They cannot travel through a vacuum because there are no particles to transmit the energy.

Explanation

An echo is caused by the reflection of sound waves off a surface or object.

When sound waves reach a surface, some of the energy is reflected back, creating an echo.

This reflected sound wave then travels back to the listener, arriving later than the original sound, causing the echo effect.

Explanation

Ultrasound has several medical applications, including:

• Pre-natal scanning
• Diagnostic imaging
• Cancer treatment

In industry, ultrasound is used for:

• Cleaning and deburring
• Welding and bonding
• Non-destructive testing

Explanation

The order of speed of sound in different mediums, from fastest to slowest, is:

• Solid (approximately 3000-6000 m/s)
• Liquid (approximately 1000-3000 m/s)
• Gas (approximately 300-400 m/s)

Explanation

• Wavelength is the distance between two consecutive points on a wave that are in phase.
• It is typically denoted by the symbol λ (lambda).

Key Points:

• Time period (T) is the time taken by the wave to complete one oscillation.
• Frequency (f) is the number of oscillations per unit time.
• Amplitude (A) is the maximum displacement of the wave from its equilibrium position.

Explanation

The speed of sound in air is affected by two main factors:

1. Temperature: As temperature increases, the speed of sound increases. This is because warmer air is less dense, allowing sound waves to travel faster.
2. Humidity: As humidity increases, the speed of sound decreases slightly. This is because water vapor in the air adds mass to the air molecules, making them slightly heavier and slower.

Explanation

Sound travels faster in solids than in gases because the molecules in a solid are packed more tightly together, allowing the energy to be transferred more efficiently.

In contrast, in a gas, the molecules are spaced farther apart and are free to move randomly, making it harder for the sound wave to propagate.

Explanation

The approximate value of the speed of sound in air at 0°C is 332 m/s.

This value is based on standard atmospheric conditions

They vary slightly with changes in temperature and pressure.