This topic contains a solution. Click here to go to the answer
« previous next »

Author Question: A zoom lens is adjusted to change its focal length from 38 mm to 304 mm. If the same amount of light ... (Read 60 times)

vinney12

  • Hero Member
  • *****
  • Posts: 586
on: Jul 29, 2018
A zoom lens is adjusted to change its focal length from 38 mm to 304 mm. If the same amount of light is to be admitted to the lens, what is the final f-number if the original f-number was 2.0?
 
  What will be an ideal response?

Question 2

The magnitude of the Poynting vector of a planar electromagnetic wave has an average value of 0.939 W/m2. The wave is incident upon a rectangular area, 1.5 m by 2.0 m, at right angles.
 
  How much total electromagnetic energy falls on the area during 1.0 minute? (c = 3.0 x 108 m/s, 0 = 4  10-7 T  m/A, 0 = 8.85  10-12 C2/N  m2)
  A) 170 J
  B) 210 J
  C) 250 J
  D) 300 J
  E) 340 J


Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
Marked as best answer by a Subject Expert

bblaney

  • Sr. Member
  • ****
  • Posts: 323
Reply #1 on: Jul 29, 2018
Answer to Question 1

16

Answer to Question 2

A


vinney12

  • Member
  • Posts: 586
Reply 2 on: Jul 29, 2018
YES! Correct, THANKS for helping me on my review

Dnite

  • Member
  • Posts: 297
Reply 3 on: Yesterday
Wow, this really help

« previous next »
 

Did you know?

Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.

Did you know?

People about to have surgery must tell their health care providers about all supplements they take.

Did you know?

In most climates, 8 to 10 glasses of water per day is recommended for adults. The best indicator for adequate fluid intake is frequent, clear urination.

Did you know?

Historic treatments for rheumatoid arthritis have included gold salts, acupuncture, a diet consisting of apples or rhubarb, nutmeg, nettles, bee venom, bracelets made of copper, prayer, rest, tooth extractions, fasting, honey, vitamins, insulin, snow collected on Christmas, magnets, and electric convulsion therapy.

Did you know?

Disorders that may affect pharmacodynamics include genetic mutations, malnutrition, thyrotoxicosis, myasthenia gravis, Parkinson's disease, and certain forms of insulin-resistant diabetes mellitus.

Pairs of heavy and light chains combine to form a Y-shaped molecule Pairs of heavy and light chains combine to form a Y-shaped molecule
Drag the labels to indicate the change in the size of the reservoir. . . Drag the labels to indicate the change in the size of the reservoir. . .
Distance from Initial Change in Membrane Potential vs. Voltage Change Relative to Initial Change Distance from Initial Change in Membrane Potential vs. Voltage Change Relative to Initial Change
A light shield over an optical sensor being installed before the rotor is attached. A light shield over an optical sensor being installed before the rotor is attached.
Check heat source for temperature. Evaluate the amount of heat given off from the source using your ... Check heat source for temperature. Evaluate the amount of heat given off from the source using your ...
Gently squeeze along the length of the arm with both hands, moving down the arm from shoulder to ... Gently squeeze along the length of the arm with both hands, moving down the arm from shoulder to ...
Video: What is Reverse Osmosis?

For a complete list of videos, visit our video library