In the given circuit, the current in resistance R3 is :
1
1 A
2
1.5 A
3
2 A
4
2.5 A
Official Solution
Correct Option: (1)
To solve for the current in resistance in the given circuit, we will follow these steps:
Identify that the resistors and are in parallel.
Calculate the equivalent resistance of the parallel combination:
The formula for resistors in parallel is:
Given, and .
So, .
Now, calculate the total resistance in the circuit. The equivalent parallel resistance is in series with and .
Total resistance
Given voltage .
.
This total current splits equally between and because they are identical resistors in parallel.
Therefore, the current through each of and is:
.
Hence, the current in resistance is 1 A, confirming the correct answer.
02
PYQ 2026
medium
physicsID: jee-main
An unpolarized light is incident on the plane interface of air-dielectric medium shown in figure. If the incident angle is equal to Brewster angle, identify the expression representing reflected wave.
1
2
3
4
Official Solution
Correct Option: (1)
Step 1: Understanding the Concept:
According to Brewster's Law, when unpolarized light is incident at the Brewster angle ( ), the reflected light is completely plane-polarized. The vibrations of the electric field in the reflected wave are perpendicular to the plane of incidence.
Step 2: Key Formula or Approach:
1. Brewster's Law: .
2. The reflected ray and refracted ray are perpendicular to each other.
3. The reflected wave must satisfy the wave equation format .
Step 3: Detailed Explanation:
1. In the geometry of Brewster's angle reflection, if the plane of incidence is the -plane, the reflected light's electric field vector will be restricted to a single direction (usually if it's perpendicular to the plane).
2. The propagation vector for reflection changes direction compared to the incident wave. If incident is in the and direction, reflection usually involves a sign change in the -component (moving away from the interface).
3. The expression must only have components perpendicular to the direction of propagation.
4. Option (A) represents a wave where the phase indicates a specific direction of propagation in the plane, consistent with reflection laws where the angle of incidence equals the angle of reflection.
Step 4: Final Answer:
The correct expression representing the reflected wave is Option (A).
03
PYQ 2026
medium
physicsID: jee-main
An unpolarized light of certain intensity passes through a combination of two polarizers whose transmission axes are at and , respectively, with respect to the horizontal axis. A third polarizer with its transmission axis at with the horizontal axis is placed between the two existing polarizers. The ratio of the output intensities with and without the third polarizer is:
1
3/4
2
4/3
3
9/4
4
4/9
Official Solution
Correct Option: (3)
Step 1: Understanding the Concept:
When unpolarized light passes through a polarizer, its intensity is reduced to half. When polarized light passes through subsequent polarizers, the intensity is governed by Malus' Law, which states that the transmitted intensity is proportional to the square of the cosine of the angle between the transmission axes.
Step 2: Key Formula or Approach:
1. Intensity after first polarizer: .
2. Malus' Law: .
Step 3: Detailed Explanation:
Let the initial intensity of unpolarized light be . After the first polarizer at , intensity is . Case 1: Without the third polarizer:
Angle between the axes of the two polarizers is .
Output intensity . Case 2: With the third polarizer at in between:
Step i: Light passes from to polarizer. Angle diff = .
.
Step ii: Light passes from to polarizer. Angle diff = .
. Calculating the Ratio:
Ratio = .
Step 4: Final Answer:
The ratio of the output intensities with and without the third polarizer is 9/4.
