Question

In a follow-up experiment, a charge of +40 pC was placed at the centre of an artificial flower at the end of a 30-cmlong stem. Bees were observed to approach no closer than 15 cm from the canter of this flower before they flew away. This observation suggests that the smallest external electric field to which bees may be sensitive is closest to which of these values? (a) 2.4 N/C; (b) 16 N/C; (c) 2.7x10-10 N/C; (d) 4.8 x 10-10 N/C.

Short answer

Option (b) $16N/C$is the closest value to which bees are sensitive too.

Step-by-step solution

Magnitude of electric field

Given,

Distance $r=15.0cm$, charge$q=40.0pc$

Now we know that the magnitude of an electric field is given by the force per charge on the test charge.

Therefore,$E=\frac{1}{4{\mathrm{\pi \epsilon }}_{\mathrm{o}}}\frac{q}{r^2}$

Calculating the electric field

We know that the value of 1/4piepinot = $\frac{1}{4{\mathrm{\pi \epsilon }}_{\mathrm{o}}}=9.0\times {10}^{9}N.m^2/C^2$. Now putting the values in the equation, we get:

$$\begin{gathered} E=\frac{1}{4{\mathrm{\pi \epsilon }}_{\mathrm{o}}}\frac{q}{r^2} \\ =\left(9.0\times {10}^{9}N.m^2/C^2\right)\frac{40.0\times {10}^{-12}C}{{\left(0.15m\right)}^2} \\ =16.0N/C \end{gathered}$$

Therefore, the closest value is$16N/C$