Answer:
<em>0.45 mm</em>
Explanation:
The complete question is
a certain fuse "blows" if the current in it exceeds 1.0 A, at which instant the fuse melts with a current density of 620 A/ cm^2. What is the diameter of the wire in the fuse?
A) 0.45 mm
B) 0.63 mm
C.) 0.68 mm
D) 0.91 mm
Current in the fuse is 1.0 A
Current density of the fuse when it melts is 620 A/cm^2
Area of the wire in the fuse = I/ρ
Where I is the current through the fuse
ρ is the current density of the fuse
Area = 1/620 = 1.613 x 10^-3 cm^2
We know that 10000 cm^2 = 1 m^2, therefore,
1.613 x 10^-3 cm^2 = 1.613 x 10^-7 m^2
Recall that this area of this wire is gotten as
A = 
where d is the diameter of the wire
1.613 x 10^-7 = 
6.448 x 10^-7 = 3.142 x 
=
d = 4.5 x 10^-4 m = <em>0.45 mm</em>
<span>To find the wavelength of a neutron can be calculated by using the formula
Wavelength=h/m x v
Where h is planck's constant
m=mass of neutron
v= velocity of the particle
By substituting the given values
Wavelength= 6.63 × 10–34 j s / 1.675 × 10–27 kg x 2 m/s^-1
Wavelength of a neutron=1.979 x 10^-7 m</span>
Let the cup is filled to height h after some time
now the total volume of coffee filled in the cup is given as



now volume of the coffee will be

here we know that



now we know that volume flow rate is given as



here y = 3 cm


so water will rise up with speed 0.71 cm/s
Answer:
A) B = 9.425 × 10^(-5) T
B) North direction
Explanation:
A) We are given;
Current in coil; I = 4.5 A
Number of turns; N = 100 turns
Radius;R = diameter/2 = 6/2 = 3 m
Formula for the magnetic field at the center of the coil is given by;
B = (μ_o•N•I)/2R
Where μ_o is a constant = 4π × 10^(-7) H/m
Thus;
B = (4π × 10^(-7) × 100 × 4.5)/(2 × 3)
B = 9.425 × 10^(-5) T
B) The direction of the force on a positive ion in water can be gotten by the application of flemmings right hand rule.
From flemmings right hand rule, we know that;
- The thumb indicates the direction of the motion of the force which is in the north direction.
- The Index finger indicates the direction of the magnetic field which is in the east direction
- The middle finger indicates the direction of magnetic field which is downwards in the west direction.
Therefore, the direction of the force as seen from flemmings right hand rule is in the north direction