A dentist wants a small mirror that, when 2.40 cm from a tooth, will produce a 4.0× upright image. What must its radius of curvature be? Follow the sign conventions.

Respuesta :

Answer:

The radius of curvature is 6.4 cm

Explanation:

Given that,

Object distance = 2.40 cm

Magnification = 4

We need to calculate the image distance

Using formula of magnification

[tex]m = -\dfrac{v}{u}[/tex]

Put the value into the formula

[tex]4=-\dfrac{v}{2.40}[/tex]

[tex]v=4\times2.40[/tex]

[tex]v = -9.6\ cm[/tex]

Negative sign shows the image of the object is same side of object

(b). We need to calculate the radius of curvature

Using mirror formula

[tex]\dfrac{2}{R}=\dfrac{1}{u}+\dfrac{1}{v}[/tex]

Put the value into the formula

[tex]\dfrac{2}{R}=\dfrac{1}{2.40}-\dfrac{1}{9.6}[/tex]

[tex]R=\dfrac{2}{0.3125}[/tex]

[tex]R=6.4\ cm[/tex]

Hence, The radius of curvature is 6.4 cm.

The radius of the mirror is 6.4cm.

How to get the radius?

The information is:

  • Distance between the mirror and the object = d = 2.40cm
  • Magnification = m = 4.

The magnification formula is given by:

[tex]m = -\frac{v}{d}[/tex]

(The negative sign is because the image is upright).

Replacing the known values, we get:

[tex]4 = -\frac{v}{2.40cm} \\v = -4*2.40cm = -9.60cm[/tex]

Now, the radius is given by:

[tex]2/R = \frac{1}{d} + \frac{1}{v}[/tex]

Replacing the values of d and v we get:

[tex]\frac{2}{R} = \frac{1}{2.40cm} + \frac{1}{-9.60cm} = 0.3125 cm^{-1}\\\\R = 2/( 0.3125 cm^{-1}) = 6.4cm[/tex]

So the radius is 6,4cm

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