The direction cosines of two lines are connected by the relations \( 1 + m - n = 0 \) and \( lm - 2mn + nl = 0 \). If \( \theta \) is the acute angle between those lines, then \( \cos \theta = \) ?
A battery of \( 6 \, \text{V} \) is connected to the circuit as shown below. The current \( I \) drawn from the battery is:
A balloon filled with an air sample occupies \( 3 \, \text{L} \) volume at \( 35^\circ \text{C} \). On lowering the temperature to \( T \), the volume decreases to \( 2.5 \, \text{L} \). The temperature \( T \) is: [Assume \( P \)-constant]