Light Intensity Homework: Solve for Unknown Intensity

[J89]

Homework Statement

A 60-cd lamp and a lamp of unknown intensity are placed 3m apart. A light meter is moved between the two lamps until it reads the same illuminance from both lamps. The light meter is then 1.5 m away from the 60-cd lamp. What is the intensity of the other lamp?

Homework Equations

E=P/d^2

The Attempt at a Solution

No clue

 

[rl.bhat]

Homework Statement

A 60-cd lamp and a lamp of unknown intensity are placed 3m apart. A light meter is moved between the two lamps until it reads the same illuminance from both lamps. The light meter is then 1.5 m away from the 60-cd lamp. What is the intensity of the other lamp?

Homework Equations

E=P/d^2

Use E = P₁/d₁^2 = P₂/d₂^2.
The point is whether the light meter is between the two lamps or outside the two lamps?

 

[nlightner]

I would approach this problem by first understanding the given information and what is being asked. It is clear that there are two lamps, one with a known intensity of 60-cd and the other with an unknown intensity. The lamps are placed 3m apart and the light meter is moved between them until it reads the same illuminance from both lamps. The final distance between the light meter and the 60-cd lamp is 1.5m.

To solve for the unknown intensity, we can use the equation E=P/d^2, where E is the illuminance, P is the intensity of the lamp, and d is the distance between the lamp and the light meter. Since we know the values of P and d for the 60-cd lamp, we can plug them into the equation and solve for E. This will give us the illuminance at a distance of 1.5m from the 60-cd lamp.

Next, we can use the same equation to solve for the unknown intensity lamp. We know the illuminance at a distance of 1.5m from this lamp (since it was the same as the 60-cd lamp), and we also know the distance between the lamp and the light meter (3m). Plugging these values into the equation will give us the unknown intensity of the lamp.

In summary, by using the equation E=P/d^2 and the given information, we can solve for the unknown intensity lamp. It is important to understand the equations and concepts involved in order to effectively solve scientific problems.