Answer with Explanation:
We are given that
Resistance of solenoid,R=4.3 ohm
Magnetic field,B=
Current,I=4.6 A
Diameter of wire,d=0.5 mm=
Radius of wire,r=

Radius of solenoid,r'=1 cm=

Resistivity of copper,
We know that

Where 
Using the formula


Number of turns of wire=
Number of turns of wire=
Hence, the number of turns of the solenoid,N=799
Magnetic field in solenoid,B=






Length of solenoid=12.5 cm
1m=100 cm
it's def. TRUE. i got the same question and i got it right
103.9 hours, if you never stopped for any reason.
Answer:
25N
Explanation:
Assuming the lab is on earth:
w = mg = 2.5 (9.81) = 25N