Add question styles

_psets/5.md

@@ -4,6 +4,7 @@ title: Problem Set 5
 
 ## (7.1)
 
+{:.question}
 Cables designed to carry signals with minimum pickup of interference often consist of a twisted pair
 of conductors surrounded by a grounded shield. Why the twist? Why the shield?
 
@@ -24,8 +25,10 @@ filter for the sorts of noise that can reach the conducting pair, with the cutof
 determined by the shield's thickness. Grounding it ensures that built up static charge has a place
 to go, though not all shields are grounded.
 
+
 ## (7.2)
 
+{:.question}
 Salt water has a conductivity ∼4 S/m. What is the skin depth at $$10^4$$ Hz?
 
 $$
@@ -36,8 +39,10 @@ $$
 \end{align*}
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+
 ## (7.3)
 
+{:.question}
 Integrate Poynting’s vector $$P = E \times H$$ to find the power flowing across a cross-sectional
 slice of a coaxial cable, and relate the answer to the current and voltage in the cable.
 
@@ -68,51 +73,63 @@ $$
 
 so we can write the total power as $$IV$$.
 
+
 ## (7.4)
 
+{:.question}
 Find the characteristic impedance and signal velocity for a transmission line consisting of two
 parallel strips with a width $$w$$ and a separation $$h$$ (Figure 7.4). You can ignore fringing
 fields by assuming that they are sections of conductors infinitely wide.
 
 ## (7.5)
 
+{:.question}
 The most common coaxial cable, RG58/U, has a dielectric with a relative permittivity of 2.26, an
 inner radius of 0.406 mm, and an outer radius of 1.48 mm.
 
 ### (a)
 
+{:.question}
 What is the characteristic impedance?
 
 ### (b)
 
+{:.question}
 What is the velocity?
 
 ### (c)
 
+{:.question}
 If a computer has a clock speed of 1 ns, how long can a length of RG58/U be and still deliver a
 pulse within one clock cycle?
 
 ### (d)
 
+{:.question}
 It is often desirable to use thinner coaxial cable to minimize size or weight but still match the
 impedance of RG58/U (to minimize reflections). If such a cable has an outer diameter of 30 mils (a
 mil is a thousandth of an inch), what is the inner diameter?
 
 ### (e)
 
+{:.question}
 For RG58/U, at what frequency does the wavelength become comparable to
 the diameter?
 
+
 ## (7.6)
 
+{:.question}
 CAT6 twisted pair cable used in ethernet networks has a propagation delay of 4.6 ns/m, and an
 impedance of 100 ohms.
 
 ### (a)
 
+{:.question}
 What is the physical length of a minimum size 64 byte frame?
 
 ### (b)
 
+{:.question}
 Now consider what would happen if a “T” connector was used to connect one CAT6 cable to two other
 ones. Estimate the reflection coefficient for a signal arriving at the T.