Recent content by Mohd Taqi

I want to calculate the radiation intensity of a cell phone which has a peak output power of about 2.0 W . The formula that I should use is I= P/A right? How to calculate the area if the question only state the distance which is 2 inch from the cell phone?

Do you have another way to solve this ?

Without repitition means our choices get reduced right .? Eg : five numbers 12345 . If can pick 3 nmbrs only, then we can't pick 333 or 444 something like tht

its like this . I don't understnd

I solved a like this . (3.6.5.4.3.2.1)/2!2!2!=270 All possible outcomes = (7!)/2!2!2!=630 P(A)=270/630=3/7 But when i try to solve b , i didnt get the answer

>4000000 and even number .. The 1st digit must always 4 and 5 and the last digit must be 2 or 4 only to make it even numbers. I tried using the same method i did in question (a) but i can't get the answer .

How many 7-digit numbers can be formed from the digits 1, 1, 2, 2, 4, 4 and 5 if repetition is not allowed. If one of these numbers is chosen at random, find the probability that it is(a) greater than 4,000,000(b) even number and greater than 4,000,000 Question b is so confusing . Help me

Oh okay .. I finally understand it. Thank you ..

So do you mean as the charge moves from left to the right its PE is decreasing ? Btw, the charge is positive or negative ?

About the formula deltaPE=-qE(deltaX) .. Whats the negative sign means ?