Opposites attract so north goes to south and Vice versa. When the same poles are facing each other they push away when they are opposites they attract.
Answer:
Electric field at a distance of 1.45 cm will be 
Explanation:
We have given the distance d = 1.45 cm = 0.0145 m
And the potential difference 
There is a relation between potential difference and electric field
Electric field at a distance d due to a potential difference is given by
, here E is electric field, V is potential difference and d is distance
So 
Answer:
option A
Explanation:
given,
distance between two masses is doubled
new distance, r' = 3 r
using gravitational force equation
............(1)
new gravitational force
now from the given condition
now, from equation (1)
now, the change in gravitational force factor is equal to 
Hence, the correct answer is option A
"Reflection" is the change direction of waves when blocked by obstacle
Answer:
5 weeks and 5 days is required to empty the lake
Explanation:
Officials begin the remove water from a full man made lake
The lake can be emptied in 4 weeks
= -1/4
A river can fill the lake up in 15 weeks
= 1/15
Let t represent the number of weeks that is required to empty the lake
= -1/t
Therefore the number of weeks it takes to empty the lake can be calculated as follows
-1/t= -1/4 + 1/15
-1/t= -11/60
Cross multiply
-11×t= -1×60
-11t= -60
t = 60/11
t= 5 5/11
Hence it takes 5 weeks and 5 days to empty the lake
