It Is Known That Birds Can Detect the Earth's Magnetic $1.2 \mathrm {~m}$

question 12

Multiple Choice

It is known that birds can detect the earth's magnetic field,but the mechanism of how they do this is not known.It has been suggested that perhaps they detect a motional emf as they fly north to south,but it turns out that the induced voltages are small compared to the voltages normally encountered in cells,so this is probably not the mechanism involved.To check this out,calculate the induced voltage across the wingtips of a wild goose with a wingspan of $1.2 \mathrm {~m}$ if it is flying directly south at $13 \mathrm {~m} / \mathrm { s }$ at a point where the earth's $\vec { B }$ field is 5.0 ×10^-5 T directed downward from the horizontal by $40 ^ { \circ }$

• A)0.50 mV
• B)0.60 mV
• C)0.78 mV
• D)0.060 mV
• E)0.25 mV

---

Definitions:

Aldosterone

A hormone produced by the adrenal glands that helps regulate blood pressure by controlling sodium and water levels in the body.

ADH

Antidiuretic Hormone, a peptide hormone secreted by the pituitary gland that regulates the body's retention of water by increasing water reabsorption in the kidneys.

Blood Plasma

The liquid component of blood where cells are suspended, comprising water, salts, proteins, and various other substances.

Medullary Osmotic Gradient

A concentration gradient of solutes in the kidney's medulla that helps in the reabsorption of water from urine, contributing to the body's water balance.