physics

[sporty04]

<p>hey guys i have physics finals tomorrow so can somebody help me with these problems please...with the explanations? :) </p>

<ol>
<li>According to the right-hand rule, if a current-carrying wire is grasped in the right hand with the thumb in the direction of the current, the four fingers will curl in the diretion of
a. the curernt's velocity, v
b. the magnetic field, B
c. the magnetic force, F (magnetic)</li>
</ol>

<p>A 2.00ohm resistor and a 12.0 ohms resistor are connected in parallel across a 20.0 V battery. What is the current flowing through the 2.00 ohms resistor?</p>

<ol>
<li><p>Two charges of 1.0 microcoulombs and -2.5microcoulombs experience a force of attraction of 1.0 N. What is the separation between charges?</p></li>
<li><p>Three resistors connected in parallel have individual values of 4.0 ohms, 6.0 ohms, and 10.0 ohms. If this combination is connected in series with a 12.0V battery and a 2.0 ohms resistor, what is the current in the 10.0 ohms resistor?</p></li>
</ol>

<p>Thanks so much!</p>

[meteman]

<ol>
<li>B</li>
<li>
V=IR
1/R= 1/2+1/20 r= 1.8181
20=(1.8181)I
I= ~11
3.
k*((Q1Q2)/(Distance^2)) K is a constant, too lazy to calculate.
4.
Calculate the voltage drop across the parallel resistors by finding the total resistance of the parallel resistors and the total current going through the whole circuit and use V=IR.
Now that you know the voltage drop, just use V=IR again and plug in 10 for R and V for the voltage drop across the parallel resistors.</li>
</ol>