Figure 22.68 shows a long straight wire just touching a loop carrying a current I1 . Both lie in the same plane. (a) What direction must the current I2 in the straight wire have to create a field at the center of the loop in the direction opposite to that created by the loop? (b) What is the ratio of I1 / I2 that gives zero field strength at the center of the loop? (c) What is the direction of the field directly above the loop under this circumstance?
1.1 Our View of the Modern Universe Monday, August 22, 2016 12:57 PM What is our place in the universe • A grand tour of the heavens ○ To survey the universe and the methods astronomersuse to study it ○ To see the measuring units used by real astronomers ○ To assess the scientific method and show how pseudoscience fails scientific tests ○ To boldly go where no class go before • The Universe ○ Some astronomersbelieve that the universe is about 14 billion years old (Maya) ○ The universe is so vast that we are actually receiving light and radio signals from the past ○ Light from the sun takes about 8 minutes ○ Light from the moontakes about 1 second ○ Light travels at a finite speed • A sense of time ○ (diagram) • Scientific Notation ○ Scientists deal with very large and very small numbers ○ Need a way to deal with all the ZEROs ○ A number between 1 and 10 times an integer power of 10 ○ 300 = 3.0 X 10 2 ○ 3,000= 3.0 X 10 3 8 ○ 300,000,000= 3.0 X 10 ○ .003 = 0.003 3.0 X 10-3 • The Metric System ○ Meters (39.37 inches) instead of feet (m) ○ Kilo means thousand ○ Mega means million ○ Milli means 1/1000(thousandth) ○ Centi means 1/100(hundreth) ○ Kilmeter is 1000 metersor about 5/8 ○ (units of measurement) ○ ○ • Definition: light-year ○ The dis
