(A) We can solve the problem by using Ohm's law, which states:

where
V is the potential difference across the electrical device
I is the current through the device
R is its resistance
For the heater coil in the problem, we know

and

, therefore we can rearrange Ohm's law to find the current through the device:

(B) The resistance of a conductive wire depends on three factors. In fact, it is given by:

where

is the resistivity of the material of the wire
L is the length of the wire
A is the cross-sectional area of the wire
Basically, we see that the longer the wire, the larger its resistance; and the larger the section of the wire, the smaller its resistance.
Answer:6.298,4.1,1.9015
Explanation:
Wavelength=
=
=4.397 m
Distance of 3rd speaker from speaker A is x
From B 78-x
Difference between the distances must be a whole number of wavelengths
First
for 1 st wavelength
2x=8.2+4.397=12.597
x=6.298m
second
For zero wavelength

2x=8.2
x=4.1m
Third

x=1.9015 m
<span>virtual, upright, and magnified</span>
Answer:
5.4 J.
Explanation:
Given,
mass of the object, m = 2 Kg
initial speed, u = 5 m/s
mass of another object,m' = 3 kg
initial speed of another orbit,u' = 2 m/s
KE lost after collusion = ?
Final velocity of the system
Using conservation of momentum
m u + m'u' = (m + m') V
2 x 5 + 3 x 2 = ( 2 + 3 )V
16 = 5 V
V = 3.2 m/s
Initial KE = 
= 
= 31 J
Final KE = 
Loss in KE = 31 J - 25.6 J = 5.4 J.