A plane mirror and a concave mirror (f = 8.20 cm) are facing each other and are separated by a distance of 25.0 cm. An object is
2 answers:
Answer:
The distance of image formed by the concave mirror is at 10.495 cm.
Explanation:
Since we know that a plane mirror forms image at a distance behind the mirror at which the object is placed in front of the mirror thus we have.
Image formed by the plane mirror is at a distance of 12.5 cm behind the plane mirror.
The image formed by the plane mirror is at a distance of 12.5 + 25.0 = 37.5 cm from the pole of the concave mirror.
Thus by mirror formula we have
Using the standard sign convention we have
u = location of object = -37.5 cm
f = focal length of mirror = -8.20 cm
Thus using the given values we obtain
Thus the image is formed at a distance of 10.495 cm from the pole of mirror towards left of mirror.
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a) Increase
b) Unchanged
c) Increase
Explanation:
a)
The charge on a capacitor charging in a RC circuit connected to a battery follows the exponential equation:
where
is the final charge stored in the capacitor, where C is the capacitance and V is the voltage of the battery
t is the time
R is the resistance of the circuit
The capacitor reaches 90% of its final charge when
Substituting and re-arranging the equation, we find:
We see that if we double the RC constant, then
So the time taken will double as well:
So, the answer is "increase"
b)
In this second part, the battery voltage is doubled.
According to the equation written in part a),
this means also that the final charge stored on the capacitor will also double.
However, the equation that gives us the time needed for the capacitor to reach 90% of its full charge is
We see that this equation does not depend at all on the voltage of the battery.
Therefore, if the battery voltage is doubled, the final charge on the capacitor will double as well, but the time needed for the capacitor to reach 90% of its charge will not change.
So the correct answer is
"unchanged"
c)
In this case, a second resistor is added in series with the original resistor of the circuit.
We know that for two resistors in series, the total resistance of the circuit is given by the sum of the individual resistances:
Since each resistance is a positive value, this means that as we add new resistors, the total resistance of the circuit increases.
Therefore in this problem, if we add a resistor in series to the original circuit, this means that the total resistance of the circuit will increase.
The time taken for the capacitor to reach 90% of its final charge is still
As we can see, this time is directly proportional to the resistance of the circuit, R: therefore, if we add a resistor in series, the resistance of the circuit will increase, and therefore this time will increase as well.
So the correct answer is
"increase"
Answer:
h₍₁₎ = 495,1 meters
h₍₂₎ = 480,4 m
h₍₃₎ = 455,9 m
...
..
Explanation:
The exercise is "free fall". t =
Solving with this formula you find the time it takes for the stone to reach the ground (T) = 102,04 s
The heights (h) according to his time (t) are found according to the formula:
h(t) = 500 - 1/2 * g * t²
Remplacing "t" with the desired time.