What are the energy transfers in a torch?
1 answer:
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Answer:
Explanation:
We know that:
where is the initial energy,
is the final energy and
is the energy lost due to friction.
so:
Where M is the mass and V is the velocity of the runner, so:
Answer:
R = 25 Ohms
Explanation:
Given the following data;
Voltage (p.d) = 15 V
Current = 0.6 A
To find the resistance of the wire;
Ohm's law states that at constant temperature, the current flowing in an electrical circuit is directly proportional to the voltage applied across the two points and inversely proportional to the resistance in the electrical circuit.
Mathematically, Ohm's law is given by the formula;
Where;
V represents voltage measured in voltage.
I represents current measured in amperes.
R represents resistance measured in ohms.
Substituting into the equation, we have;
R = 25 Ohms
a) Potential difference needed: 10,000 V
b) Because the potential difference in the house is maximum 230 V
Explanation:
a)
The relationship between current, potential difference and resistance in a conductor is given by Ohm's law:
where
V is the potential difference
R is the resistance
I is the current
The resistance of the human body is estimated to be as high as for a dry body and as low as
for a wet body: in this problem, we use a value in the middle,
Therefore, the potential difference needed to produce a current of
is
b)
Here we want to estimate if it is likely or not to get injured by an electric current in a house.
The amount of current that can be fatal is . From part a), we saw that in order to produce this current through the human body, a potential difference of
is needed.
However, the electricity that reaches the houses and then is connected to the household appliances has a potential difference of
V = 230 V
This value is much lower than 10,000 V, therefore the electricity in the house is unlikely to cause injures to human body.
Learn more about potential difference:
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