Which of these statements is true? I. As wavelength increases, frequency decreases. II. As energy increases, frequency increases. III. As wavelength increases, energy decreases. IV. The product of wavelength and frequency is constant
The Correct Answer and Explanation is:
Correct Answer: All statements I, II, III, and IV are true.
Explanation
These four statements describe key relationships among wavelength, frequency, and energy in the context of electromagnetic waves or any wave phenomena.
Statement I: As wavelength increases, frequency decreases.
This is true. The wavelength and frequency of a wave are inversely proportional. This means if one increases, the other must decrease, assuming the speed of the wave remains constant. The formula that shows this is:v=f×λv = f \times \lambdav=f×λ
Where:
- vvv is the speed of the wave (for light, it’s about 3.0×1083.0 \times 10^83.0×108 meters per second),
- fff is frequency (in hertz),
- λ\lambdaλ is wavelength (in meters).
Statement II: As energy increases, frequency increases.
This is true. Energy and frequency are directly proportional. According to the equation:E=h×fE = h \times fE=h×f
Where:
- EEE is energy (in joules),
- hhh is Planck’s constant (6.626×10−346.626 \times 10^{-34}6.626×10−34 J·s),
- fff is frequency.
So, when frequency increases, energy increases too.
Statement III: As wavelength increases, energy decreases.
This is also true. Since wavelength and frequency are inversely related, and energy is directly related to frequency, energy and wavelength must also be inversely related. Longer wavelengths have lower energy.
Statement IV: The product of wavelength and frequency is constant.
This is true for waves moving through the same medium. The speed of a wave is constant, and is given by:v=f×λv = f \times \lambdav=f×λ
So if the wave’s speed is constant, increasing one (frequency or wavelength) causes the other to decrease, keeping the product the same.
In conclusion, all four statements accurately describe the fundamental wave relationships in physics.
