The work of which scientist(s) helped to explain light's ability to propagate through a vacuum?
A. Maxwell
==B. Davisson and Germer
C. Fresnel, Fraunhofer, and Arago
D. Newton
An object that has a height of 0.4 meter is placed at a distance of 0.7 meter from a concave spherical mirror. An image is formed in front of the mirror and has a height of 0.35 meter. How far from the mirror is the image located?
A. 0.8000 m
==B. 0.6125 m
C. 0.2000 m
D. 0.4275 m
If we're interested in knowing the rate at which light energy is received by a unit of area on a particular surface, we're really trying to figure out the
== A. illuminance of a surface.
B. luminous intensity.
C. luminous flux.
D. incandescence.
In any one material, all electromagnetic waves have the same
==A. velocity.
B. frequency.
C. wavelength.
D. amplitude.
The illuminance on a surface is 6 lux and the surface is 4 meters from the light source. What is the intensity of the source?
A. 72 candelas
==B. 96 candelas
C. 24 candelas
D. 144 candelas
Which of the following devices is associated with the reception of radio signals?
A. Microphone
==B. Demodulator
C. Transmitting antenna
D. Oscillator
Suppose that an electric charge is produced on one part of a body. If the charge spreads through the entire body, the body is most likely made of
A. oil.
==B. metal.
C. plastic.
D. porcelain.
Which of the following accurately describes junction diodes?
A. Free electrons are concentrated in the P-type material and holes form in the N-type material.
B. In a forward-biased setup, large numbers of charge carriers will be pulled across the junction and result in a large current.
==C. The negative terminal of the source of voltage is connected to the N-type material within a reverse-biased setup.
D. Only a small current will flow through the diode in the forward-biased setup.
Imagine that an uncharged pith ball is brought into the electrostatic field of a charged rod. The side of the pith ball closest to the negatively charged end of the rod will
A. be given a negative charge produced by the movement of electrons from the rod.
B. not experience any induced charge and remain neutral.
==C. be given a positive charge produced by the movement of electrons to the other end of the ball.
D. be given a negative charge produced by the movement of electrons from the other end of the ball.
A complete circuit contains two parallel-connected devices and a generator for providing the electromotive force. The resistance of the first device is 12 ohms, the resistance of the second device is 4 ohms, and the voltage developed by the generator is 40 V. What is the magnitude of the current flowing through the first device?
A. 8 A
B. 10 A
==C. 3.33 A
D. 13.32 A
Are they correct?
12. The work of which scientist(s) helped to explain light's ability to propagate through a vacuum?
A. Fresnel, Fraunhofer, and Arago
B. Davisson and Germer
C. Maxwell
D. Newton
12. The work of which scientist(s) helped to explain light's ability to propagate through a vacuum?
A. Fresnel, Fraunhofer, and Arago
B. Davisson and Germer
C. Maxwell
D. Newton