Final answer:
Intensity in physics refers to the strength of a wave, such as light, and is halved if it's reduced to 50%. Changes in intensity can result from using a polarizing filter or distance changes from the light source, following the inverse square law. To increase the intensity of a wave, the amplitude of the fields must be increased.
Step-by-step explanation:
Understanding Intensity in Physics
When the intensity of light is said to be reduced to 50%, it implies that the light's strength is half of its original value. For example, if initially the intensity of light was 1.2 W/m², now it would be 0.6 W/m². In scenarios where the intensity of light is affected by distance, according to the inverse square law, if you move twice as far away from the light source, the intensity decreases to one quarter of the original value, which can be calculated as (1/2)² = 1/4 of the initial intensity.
Different physical situations would lead to changes in intensity. For example, if a polarizing filter reduces the intensity of polarized light to 50% of its initial value, both the electric and magnetic field amplitudes are reduced by a factor of √0.5, because intensity is proportional to the square of the amplitude of these fields.
To increase intensity of a wave by a factor of 50, the amplitude should be increased by a factor of √50 since intensity is proportional to the square of the amplitude. Finding the reduction in intensity or calculating the necessary conditions to change the intensity is a common problem in physics, particularly in the study of waves and optics.