Induction & Tranformer Problems

[mustang]

Problem 1.
A single circular loop with a radius of 28cm is palced in a uniform external magnetic field with a strength of 0.54 T so that the plane of the coil is perpendicular to the field. The coil is pulled steadily out of the field in 0.35s.
Find the average induced emf during this interval. Asnwer in V.
Note: what formula should i use?

Problem 5.
A 38-turn coil with an area of 1.8*10^-3 m^2 is dropped from a position where B=0.0T to a new position where B= 0.68T. The displacement occurs in 0.29 s and the area of the coil is perpendicular to the magnetic field lines.
What is the resulting average emf induced in the coil? Answe in V.
Note: How do I start?

Problem 7.
A step-up transformer for long-range transmission of electric power is used to create a potential difference of 129530 V across the secondary. The potential difference across the primary is 161 V and the secondary has 26000 turns.
How many turns are in the primary? Answer in units of turns.
Note: What is the formula I should?

Problem 10.
A transformer is used to convert 120 V to 16V in order to power a toy electric train. There are 240 turns in the primary.
How many turns should there be in the secondary? Answer in units of turns.
Note: I don't know where to start.

 

[member 553083]

Solution: Problem 1: The formula to use is Faraday's Law of Induction, which states that the induced emf is equal to the rate of change of flux through a loop. The average induced emf can be calculated by taking the total change in flux over the given time interval and dividing it by the time: E_avg = (ΔΦ/Δt) = ((B*π*r^2)/(0.35s)) = 10.9 V Problem 5: The formula to use here is Faraday's Law of Induction, which states that the induced emf is equal to the rate of change of flux through a loop. The average induced emf can be calculated by taking the total change in flux over the given time interval and dividing it by the time: E_avg = (ΔΦ/Δt) = ((B*A*N)/(0.29s)) = 6.3 V Problem 7: The formula to use here is the transformation ratio, which states that the ratio of the primary turns to the secondary turns is equal to the ratio of the primary voltage to the secondary voltage: N_primary/N_secondary = V_primary/V_secondary Therefore, the number of turns in the primary can be calculated as: N_primary = (V_primary/V_secondary)*N_secondary = (161V/129530V)*26000 turns = 19.6 turns Problem 10: The formula to use here is the transformation ratio, which states that the ratio of the primary turns to the secondary turns is equal to the ratio of the primary voltage to the secondary voltage: N_primary/N_secondary = V_primary/V_secondary Therefore, the number of turns in the secondary can be calculated as: N_secondary = (V_secondary/V_primary)*N_primary = (16V/120V)*240 turns = 32 turns

 

[M98Ranger]

For Problem 1, the formula to use is Faraday's law of induction, which states that the induced emf is equal to the rate of change of magnetic flux through the coil. In this case, the average induced emf can be calculated by dividing the change in magnetic flux by the time interval. The formula is written as E = ΔΦ/Δt, where E is the induced emf, ΔΦ is the change in magnetic flux, and Δt is the time interval. In this problem, the change in magnetic flux can be calculated by multiplying the magnetic field strength by the area of the coil, since the coil is perpendicular to the field. The average induced emf can then be calculated by dividing this change in magnetic flux by the given time interval.

For Problem 5, the same formula can be used, but the change in magnetic flux must be calculated differently. Since the coil is dropped, the change in magnetic flux is equal to the initial magnetic flux minus the final magnetic flux. The initial magnetic flux can be calculated by multiplying the initial magnetic field strength by the initial area of the coil, and the final magnetic flux can be calculated by multiplying the final magnetic field strength by the final area of the coil. The average induced emf can then be calculated using the same formula as Problem 1.

For Problem 7, the formula to use is the transformer equation, which states that the ratio of the number of turns in the primary coil to the number of turns in the secondary coil is equal to the ratio of the input voltage to the output voltage. In this problem, the input voltage and number of turns in the primary are given, so the number of turns in the secondary can be calculated by rearranging the formula to solve for the number of turns in the secondary.

For Problem 10, the same transformer equation can be used, but it must be rearranged to solve for the number of turns in the secondary. The input voltage and number of turns in the primary are given, and the output voltage is also given. Solving for the number of turns in the secondary will give the solution.