How is thermal energy transferred?
2 answers:
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Answer:
initial and final temperatures of both the water and metal, mass of the metal, and mass of the water
Explanation:
Heat lost by the metal,
Heat gained by the water in the calorimeter,
For energy to be conserved in the system, the heat lost by the metal will equal the heat gain by the water in the calorimeter.
Where,
m is the mass of the metal
c is specific heat capacity of the metal
t₂ is the final temperature of the metal
t₁ is the initial temperature of the metal
is the mass of the water
is specific heat capacity of water
is the final temperature of water
is the initial temperature of water
From the question given, specific heat capacity of the water is known, the quantities to be measured are;
Initial and final temperatures of both the water and metal,
Mass of the metal, and mass of the water
Answer:
Transformers are used to increase or decrease the voltage of AC currents
Explanation:
A transformer is a device consisting of two coils (called primary and secondary coil) wrapped at the two sides of a soft iron core. When an AC current is present in the primary coil, it induces a magnetic field inside the core, and the presence of this changing magnetic field induces a voltage (and a current) into the secondary coil.
The voltages in the primary and the secondary coil are related by the transformer equation:
where
Vp, Vs are the voltages in the primary and secondary coil
Np, Ns are the number of turns in the primary and secondary coil
There are two types of transformers:
- Step-up transformers: these have , so that
, which means that they increase the voltage. They are used to increase the voltage of the AC current produced by the power plants, before being sent into the transmission lines.
- Step-down transformers: these have , so that
, which means that they decrease the voltage. They are used at the end of the transmission lines, before the houses, in order to decrease the voltage and allow the household appliances to work properly (in fact, household appliances need lower voltages to work)