Respuesta :
Answer:
Explanation:
length of the solenoid, l = 20 cm = 0.2 m
radius, r = 3 cm
current in the coil = Io
Magnetic field = Bo
The magnetic field due to the current carrying solenoid is
[tex]B_{0}=\mu_{0}nI_{0}[/tex] ..... (1)
where, n is the number of turns per unit length.
so, increasing the number of turns by four times in 20 cm length solenoid, the magnetic field is 4 times. option (a)
And, by taking half the length of the solenoid, and the double of number of turns, the magnetic field due to the solenoid becomes 4 times. option (d)
If we wish to produce a field that is 4-times larger, double the current in the wire, and double the number of turns in the 20-cm long solenoid.
The given parameters:
- length of the solenoid, l = 20 cm
- number of turns of the solenoid, N = 100
- current in the coil, = Io
- magnetic field, = Bo
The magnitude of the magnetic field at the center of the solenoid is calculated as follows;
[tex]B = \mu_o nI[/tex]
where;
- n is the number of turns per length (N/L)
[tex]B = \frac{\mu_o NI}{L} \\\\B_1L_1 = B_2L_2\\\\L_2 = \frac{B_1L_1}{B_2} \\\\L_2 = \frac{B_1 \times L_1}{4B_1} \\\\L _2 = \frac{1}{4} L_1[/tex]
The magnetic field, current and number of turns are directly proportional;
[tex]B = \mu_0 nI\\\\\frac{B_1}{N_1I_1} = \frac{B_2}{N_2I_2} \\\\N_2 I_2 = \frac{B_2}{B_1} N_1I_1\\\\N_2 I_2 = \frac{4B_1}{B_1} N_1I_1\\\\N_2I_2 = 4N_1I_1\\\\N_2I_2 = 2N_1 2I_1[/tex]
Thus, we can conclude that if we wish to produce a field that is 4-times larger, double the current in the wire, and double the number of turns in the 20-cm long solenoid.
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