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m_a_m_a [10]
3 years ago
11

Definition of phosphorescence

Physics
1 answer:
Sergio [31]3 years ago
4 0
Light emitted by substance without combustion or perceptible heat emission of radiation in a similar manner to florescence but on a longer time scale so that emission continues after excitation ceases.
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Three identical resistors are connected in parallel. The equivalent resistance increases by 630 when one resistor is removed and
strojnjashka [21]

Answer:

each resistor is 540 Ω

Explanation:

Let's assign the letter R to the resistance of the three resistors involved in this problem. So, to start with, the three resistors are placed in parallel, which results in an equivalent resistance R_e defined by the formula:

\frac{1}{R_e}=\frac{1}{R} } +\frac{1}{R} } +\frac{1}{R} \\\frac{1}{R_e}=\frac{3}{R} \\R_e=\frac{R}{3}

Therefore, R/3 is the equivalent resistance of the initial circuit.

In the second circuit, two of the resistors are in parallel, so they are equivalent to:

\frac{1}{R'_e}=\frac{1}{R} +\frac{1}{R}\\\frac{1}{R'_e}=\frac{2}{R} \\R'_e=\frac{R}{2} \\

and when this is combined with the third resistor in series, the equivalent resistance (R''_e) of this new circuit becomes the addition of the above calculated resistance plus the resistor R (because these are connected in series):

R''_e=R'_e+R\\R''_e=\frac{R}{2} +R\\R''_e=\frac{3R}{2}

The problem states that the difference between the equivalent resistances in both circuits is given by:

R''_e=R_e+630 \,\Omega

so, we can replace our found values for the equivalent resistors (which are both in terms of R) and solve for R in this last equation:

\frac{3R}{2} =\frac{R}{3} +630\,\Omega\\\frac{3R}{2} -\frac{R}{3} = 630\,\Omega\\\frac{7R}{6} = 630\,\Omega\\\\R=\frac{6}{7} *630\,\Omega\\R=540\,\Omega

8 0
3 years ago
An object traveling at a constant speed but with a changing direction is accelerating.
prohojiy [21]

Strange as it may seem, that's true. (choice 'a'.)

"Acceleration" doesn't mean "speeding up".  It means ANY change in
the speed or direction of motion.  So a car with the brakes applied
and slowing down, and a point on the rim of a bicycle wheel that's
turning at a constant rate, are both accelerating.

6 0
3 years ago
Read 2 more answers
PLEASE PLEASE HELP!!!!!!
Whitepunk [10]

Answer:

the answer is B

Explanation:

The atomic mass of an atom is the sum of the protons plus neutrons it has.

7 0
3 years ago
Which of the following is a definition of glass transition temperature?
aleksandr82 [10.1K]

Answer:

c. The temperature at which a glass transforms from a solid to liquid.

Explanation:

The glass transition temperature is said to be a temperature range when a polymer structure transition from a glass or hardy(solid) material to a rubber like or viscous liquid material.

The glass transition temperature is an important property that is critical in product design.

5 0
4 years ago
An electrical device in which a long wire is wound into a succession of closely spaced loops around a n insulating core is calle
Iteru [2.4K]

Answer:

Solenoid I think.

Explanation:

6 0
3 years ago
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