A battery is a device that produces electricity by transforming chemical energy into electrical energy. a battery does work on e
1 answer:
(Missing question is: which of the following statements are true?)
a) A battery does work on electric charges to bring them to a position of higher electric potential energy so that they can flow through a circuit to a lower potential energy --> TRUE
That's true: the battery does the work to move the charges to one end of its terminal thus creating a potential difference between the two terminals. Then, when it is connected to the circuit, charges start to flow to the terminal at lower potential (through the circuit)
b) the potential difference between the terminals of a battery, when no current flows to an external circuit, is referred to as the terminal voltage --> FALSE
This is false: when no current flows, it is called e.m.f. (electromotive force)
c) <span>the internal resistance of a battery decreases with decreasing temperature
--> TRUE
In fact, the dependence of a resistance with the temperature is:
</span>![R=R_0 [1+\alpha(T-T_0)]](https://tex.z-dn.net/?f=R%3DR_0%20%5B1%2B%5Calpha%28T-T_0%29%5D)
with
being generally positive, therefore the value of the resistance is proportional to T, and when T decreases, R decreases as well.
d) a battery is a device that produces electricity by transforming chemical energy into electrical energy --> TRUEThat's true: a battery uses chemical reactions to create a potential difference between the two terminals that can be exploited to make charges flowing through a circuit.
a) A battery does work on electric charges to bring them to a position of higher electric potential energy so that they can flow through a circuit to a lower potential energy --> TRUE
That's true: the battery does the work to move the charges to one end of its terminal thus creating a potential difference between the two terminals. Then, when it is connected to the circuit, charges start to flow to the terminal at lower potential (through the circuit)
b) the potential difference between the terminals of a battery, when no current flows to an external circuit, is referred to as the terminal voltage --> FALSE
This is false: when no current flows, it is called e.m.f. (electromotive force)
c) <span>the internal resistance of a battery decreases with decreasing temperature
--> TRUE
In fact, the dependence of a resistance with the temperature is:
</span>
with
d) a battery is a device that produces electricity by transforming chemical energy into electrical energy --> TRUEThat's true: a battery uses chemical reactions to create a potential difference between the two terminals that can be exploited to make charges flowing through a circuit.
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Answer:
The time is 16 min.
Explanation:
Given that,
Time = 120 sec
We need to calculate the moment of inertia
Using formula of moment of inertia
If the disk had twice the radius and twice the mass
The new moment of inertia
We know,
The torque is
We need to calculate the initial rotation acceleration
Using formula of acceleration
Put the value in to the formula
We need to calculate the new rotation acceleration
Using formula of acceleration
Put the value in to the formula
Rotation speed is same.
We need to calculate the time
Using formula angular velocity
Put the value into the formula
Hence, The time is 16 min.
Answer: The unpolarized light's intensity is reduced by the factor of two when it passes through the polaroid and becomes linearly polarized in the plane of the Polaroid. When the polarized light passes through the polaroid with the plane of polarization at an angle with respect to the polarization plane of the incoming light, the light's intensity is reduced by the factor of
(this is the Law of Malus).
Explanation: Let us say we have a beam of unpolarized light of intensity that passes through two parallel Polaroid discs with the angle of
between their planes of polarization. We are asked to find
such that the intensity of the outgoing beam is
. To solve this we follow the steps below:
Step 1. It is known that when the unpolarized light passes through a polaroid its intensity is reduced by the factor of two, meaning that the intensity of the beam passing through the first polaroid is
This beam also becomes polarized in the plane of the first polaroid.
Step 2. Now the polarized beam hits the surface of the second polaroid whose polarization plane is at an angle with respect to the plane of the polarization of the beam. After passing through the polaroid, the beam remains polarized but in the plane of the second polaroid and its intensity is reduced, according to the Law of Malus, by the factor of
This yields
. Substituting from the previous step we get
yielding
and finally,