An object is placed 15cm in front of a concave mirror of radius 40cm. The image formed
virtual and 60cm behind the mirror
real and 60cm behind the mirror
virtual and at infinity
real and at infinity
virtual and 40cm from the mirror
Explanation
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the ans is option A .F=RADIUS/2 :. F=40/2.=20 1/20=1/v+1/15 f=20*15/15-20 =300/-5 =-60cm dat z y it z virtue, the corr opt z A
1÷V +1÷u=1÷f
u is the object distance= 15
V is the image distance=?
f is the focal length,it is given by radius divided by 2 therefore f =40÷2=20
1÷V + 1÷15 = 1÷20
1÷V= 1÷20 - 1÷15
find the number that both 20 and 15 can divide, that number is 60,
20 divide 60 would give you 3 and 15 divide 60 would give you 4
3-4÷60 = -1÷60
1÷V = -1÷60
Cross multiply and you would get
-V= 60
multiply both sides by minus and you would get
V= -60
Since the image distance is negative it means that the image is virtual,if it's positive then the image is real.
D ANSWER IS A JOOR BCOS D IMAGE DISTANCE IS NEGATIVE.AND Fequals r over 2 thouh it is real but it is still negative.
